diff --git a/openstackclient/tests/identity/v2_0/test_catalog.py b/openstackclient/tests/identity/v2_0/test_catalog.py
index ff1d993e98..adbf8c30e6 100644
--- a/openstackclient/tests/identity/v2_0/test_catalog.py
+++ b/openstackclient/tests/identity/v2_0/test_catalog.py
@@ -72,7 +72,9 @@ class TestCatalogList(TestCatalog):
         verifylist = []
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
         self.sc_mock.service_catalog.get_data.assert_called_with()
 
@@ -114,7 +116,9 @@ class TestCatalogList(TestCatalog):
         verifylist = []
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
         self.sc_mock.service_catalog.get_data.assert_called_with()
 
diff --git a/openstackclient/tests/identity/v2_0/test_endpoint.py b/openstackclient/tests/identity/v2_0/test_endpoint.py
index 11696f4660..9331b2565c 100644
--- a/openstackclient/tests/identity/v2_0/test_endpoint.py
+++ b/openstackclient/tests/identity/v2_0/test_endpoint.py
@@ -164,7 +164,9 @@ class TestEndpointList(TestEndpoint):
         verifylist = []
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         self.endpoints_mock.list.assert_called_with()
@@ -188,7 +190,9 @@ class TestEndpointList(TestEndpoint):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         self.endpoints_mock.list.assert_called_with()
diff --git a/openstackclient/tests/identity/v2_0/test_project.py b/openstackclient/tests/identity/v2_0/test_project.py
index 69b2926871..ad4ab26555 100644
--- a/openstackclient/tests/identity/v2_0/test_project.py
+++ b/openstackclient/tests/identity/v2_0/test_project.py
@@ -322,7 +322,9 @@ class TestProjectList(TestProject):
         verifylist = []
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
         self.projects_mock.list.assert_called_with()
 
@@ -343,7 +345,9 @@ class TestProjectList(TestProject):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
         self.projects_mock.list.assert_called_with()
 
diff --git a/openstackclient/tests/identity/v2_0/test_role.py b/openstackclient/tests/identity/v2_0/test_role.py
index b660c61491..f884720f7b 100644
--- a/openstackclient/tests/identity/v2_0/test_role.py
+++ b/openstackclient/tests/identity/v2_0/test_role.py
@@ -260,7 +260,9 @@ class TestRoleList(TestRole):
         verifylist = []
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         self.roles_mock.list.assert_called_with()
@@ -330,7 +332,9 @@ class TestUserRoleList(TestRole):
         verifylist = []
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         self.roles_mock.roles_for_user.assert_called_with(
@@ -387,7 +391,9 @@ class TestUserRoleList(TestRole):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         self.roles_mock.roles_for_user.assert_called_with(
diff --git a/openstackclient/tests/identity/v2_0/test_service.py b/openstackclient/tests/identity/v2_0/test_service.py
index 9c0cf8cded..27a592d5cf 100644
--- a/openstackclient/tests/identity/v2_0/test_service.py
+++ b/openstackclient/tests/identity/v2_0/test_service.py
@@ -214,7 +214,9 @@ class TestServiceList(TestService):
         verifylist = []
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         self.services_mock.list.assert_called_with()
@@ -237,7 +239,9 @@ class TestServiceList(TestService):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         self.services_mock.list.assert_called_with()
diff --git a/openstackclient/tests/identity/v2_0/test_user.py b/openstackclient/tests/identity/v2_0/test_user.py
index 0c4370f25c..62d78c16b2 100644
--- a/openstackclient/tests/identity/v2_0/test_user.py
+++ b/openstackclient/tests/identity/v2_0/test_user.py
@@ -448,7 +448,9 @@ class TestUserList(TestUser):
         verifylist = []
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         self.users_mock.list.assert_called_with(tenant_id=None)
@@ -466,7 +468,9 @@ class TestUserList(TestUser):
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
         project_id = identity_fakes.PROJECT_2['id']
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         self.users_mock.list.assert_called_with(tenant_id=project_id)
@@ -483,7 +487,9 @@ class TestUserList(TestUser):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         self.users_mock.list.assert_called_with(tenant_id=None)
diff --git a/openstackclient/tests/identity/v3/test_catalog.py b/openstackclient/tests/identity/v3/test_catalog.py
index 6bb962de09..cfae05a1c9 100644
--- a/openstackclient/tests/identity/v3/test_catalog.py
+++ b/openstackclient/tests/identity/v3/test_catalog.py
@@ -68,7 +68,9 @@ class TestCatalogList(TestCatalog):
         verifylist = []
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
         self.sc_mock.service_catalog.get_data.assert_called_with()
 
diff --git a/openstackclient/tests/identity/v3/test_consumer.py b/openstackclient/tests/identity/v3/test_consumer.py
index 4e807562fc..7f6af7348c 100644
--- a/openstackclient/tests/identity/v3/test_consumer.py
+++ b/openstackclient/tests/identity/v3/test_consumer.py
@@ -121,7 +121,9 @@ class TestConsumerList(TestOAuth1):
         verifylist = []
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
         self.consumers_mock.list.assert_called_with()
 
diff --git a/openstackclient/tests/identity/v3/test_domain.py b/openstackclient/tests/identity/v3/test_domain.py
index 969c2df7ef..71a48b4ed2 100644
--- a/openstackclient/tests/identity/v3/test_domain.py
+++ b/openstackclient/tests/identity/v3/test_domain.py
@@ -215,7 +215,9 @@ class TestDomainList(TestDomain):
         verifylist = []
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
         self.domains_mock.list.assert_called_with()
 
diff --git a/openstackclient/tests/identity/v3/test_endpoint.py b/openstackclient/tests/identity/v3/test_endpoint.py
index fb88e004cd..816f3f9238 100644
--- a/openstackclient/tests/identity/v3/test_endpoint.py
+++ b/openstackclient/tests/identity/v3/test_endpoint.py
@@ -315,7 +315,9 @@ class TestEndpointList(TestEndpoint):
         verifylist = []
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
         self.endpoints_mock.list.assert_called_with()
 
@@ -342,7 +344,9 @@ class TestEndpointList(TestEndpoint):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         # Set expected values
@@ -374,7 +378,9 @@ class TestEndpointList(TestEndpoint):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         # Set expected values
@@ -406,7 +412,9 @@ class TestEndpointList(TestEndpoint):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         # Set expected values
diff --git a/openstackclient/tests/identity/v3/test_group.py b/openstackclient/tests/identity/v3/test_group.py
index 59a3681971..c5f5dbca7b 100644
--- a/openstackclient/tests/identity/v3/test_group.py
+++ b/openstackclient/tests/identity/v3/test_group.py
@@ -85,7 +85,9 @@ class TestGroupList(TestGroup):
         verifylist = []
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         # Set expected values
@@ -110,7 +112,9 @@ class TestGroupList(TestGroup):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         # Set expected values
@@ -135,7 +139,9 @@ class TestGroupList(TestGroup):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         # Set expected values
@@ -160,7 +166,9 @@ class TestGroupList(TestGroup):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         # Set expected values
diff --git a/openstackclient/tests/identity/v3/test_identity_provider.py b/openstackclient/tests/identity/v3/test_identity_provider.py
index 50a922b89e..7591151091 100644
--- a/openstackclient/tests/identity/v3/test_identity_provider.py
+++ b/openstackclient/tests/identity/v3/test_identity_provider.py
@@ -290,7 +290,9 @@ class TestIdentityProviderList(TestIdentityProvider):
         verifylist = []
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         self.identity_providers_mock.list.assert_called_with()
diff --git a/openstackclient/tests/identity/v3/test_project.py b/openstackclient/tests/identity/v3/test_project.py
index 36540201d0..61b6d2c6f7 100644
--- a/openstackclient/tests/identity/v3/test_project.py
+++ b/openstackclient/tests/identity/v3/test_project.py
@@ -464,7 +464,9 @@ class TestProjectList(TestProject):
         verifylist = []
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
         self.projects_mock.list.assert_called_with()
 
@@ -480,7 +482,9 @@ class TestProjectList(TestProject):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
         self.projects_mock.list.assert_called_with()
 
@@ -511,7 +515,9 @@ class TestProjectList(TestProject):
 
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
         self.projects_mock.list.assert_called_with(
             domain=identity_fakes.domain_id)
diff --git a/openstackclient/tests/identity/v3/test_region.py b/openstackclient/tests/identity/v3/test_region.py
index 9ac9ddf8ed..c54480ee64 100644
--- a/openstackclient/tests/identity/v3/test_region.py
+++ b/openstackclient/tests/identity/v3/test_region.py
@@ -193,7 +193,9 @@ class TestRegionList(TestRegion):
         verifylist = []
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
         self.regions_mock.list.assert_called_with()
 
@@ -209,7 +211,9 @@ class TestRegionList(TestRegion):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
         self.regions_mock.list.assert_called_with(
             parent_region_id=identity_fakes.region_parent_region_id)
diff --git a/openstackclient/tests/identity/v3/test_role.py b/openstackclient/tests/identity/v3/test_role.py
index 227b06439e..7379fe8bc0 100644
--- a/openstackclient/tests/identity/v3/test_role.py
+++ b/openstackclient/tests/identity/v3/test_role.py
@@ -364,7 +364,9 @@ class TestRoleList(TestRole):
         verifylist = []
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         self.roles_mock.list.assert_called_with()
@@ -383,7 +385,9 @@ class TestRoleList(TestRole):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         # Set expected values
@@ -409,7 +413,9 @@ class TestRoleList(TestRole):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         # Set expected values
@@ -437,7 +443,9 @@ class TestRoleList(TestRole):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         # Set expected values
@@ -472,7 +480,9 @@ class TestRoleList(TestRole):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         # Set expected values
@@ -507,7 +517,9 @@ class TestRoleList(TestRole):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         # Set expected values
@@ -542,7 +554,9 @@ class TestRoleList(TestRole):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         # Set expected values
diff --git a/openstackclient/tests/identity/v3/test_role_assignment.py b/openstackclient/tests/identity/v3/test_role_assignment.py
index 5723a33477..c7ed289bac 100644
--- a/openstackclient/tests/identity/v3/test_role_assignment.py
+++ b/openstackclient/tests/identity/v3/test_role_assignment.py
@@ -86,7 +86,9 @@ class TestRoleAssignmentList(TestRoleAssignment):
         verifylist = []
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         self.role_assignments_mock.list.assert_called_with(
@@ -146,7 +148,9 @@ class TestRoleAssignmentList(TestRoleAssignment):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         self.role_assignments_mock.list.assert_called_with(
@@ -206,7 +210,9 @@ class TestRoleAssignmentList(TestRoleAssignment):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         self.role_assignments_mock.list.assert_called_with(
@@ -266,7 +272,9 @@ class TestRoleAssignmentList(TestRoleAssignment):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         self.role_assignments_mock.list.assert_called_with(
@@ -326,7 +334,9 @@ class TestRoleAssignmentList(TestRoleAssignment):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         self.role_assignments_mock.list.assert_called_with(
@@ -384,7 +394,9 @@ class TestRoleAssignmentList(TestRoleAssignment):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         self.role_assignments_mock.list.assert_called_with(
@@ -444,7 +456,9 @@ class TestRoleAssignmentList(TestRoleAssignment):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         self.role_assignments_mock.list.assert_called_with(
diff --git a/openstackclient/tests/identity/v3/test_service.py b/openstackclient/tests/identity/v3/test_service.py
index c609142cd7..624606b7cf 100644
--- a/openstackclient/tests/identity/v3/test_service.py
+++ b/openstackclient/tests/identity/v3/test_service.py
@@ -225,7 +225,9 @@ class TestServiceList(TestService):
         verifylist = []
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         self.services_mock.list.assert_called_with()
@@ -248,7 +250,9 @@ class TestServiceList(TestService):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         self.services_mock.list.assert_called_with()
diff --git a/openstackclient/tests/identity/v3/test_service_provider.py b/openstackclient/tests/identity/v3/test_service_provider.py
index 24fa7c7b64..fb7576f1cc 100644
--- a/openstackclient/tests/identity/v3/test_service_provider.py
+++ b/openstackclient/tests/identity/v3/test_service_provider.py
@@ -220,7 +220,9 @@ class TestServiceProviderList(TestServiceProvider):
         verifylist = []
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         self.service_providers_mock.list.assert_called_with()
diff --git a/openstackclient/tests/identity/v3/test_trust.py b/openstackclient/tests/identity/v3/test_trust.py
index b90e78159b..56d4d13477 100644
--- a/openstackclient/tests/identity/v3/test_trust.py
+++ b/openstackclient/tests/identity/v3/test_trust.py
@@ -167,7 +167,9 @@ class TestTrustList(TestTrust):
         verifylist = []
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         self.trusts_mock.list.assert_called_with()
diff --git a/openstackclient/tests/identity/v3/test_unscoped_saml.py b/openstackclient/tests/identity/v3/test_unscoped_saml.py
index 6a79909462..c2f14493a2 100644
--- a/openstackclient/tests/identity/v3/test_unscoped_saml.py
+++ b/openstackclient/tests/identity/v3/test_unscoped_saml.py
@@ -52,7 +52,9 @@ class TestProjectList(TestUnscopedSAML):
         verifylist = []
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         self.projects_mock.list.assert_called_with()
@@ -101,7 +103,9 @@ class TestDomainList(TestUnscopedSAML):
         verifylist = []
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         self.domains_mock.list.assert_called_with()
diff --git a/openstackclient/tests/identity/v3/test_user.py b/openstackclient/tests/identity/v3/test_user.py
index 641def0e8a..f77809d0ed 100644
--- a/openstackclient/tests/identity/v3/test_user.py
+++ b/openstackclient/tests/identity/v3/test_user.py
@@ -552,7 +552,9 @@ class TestUserList(TestUser):
         verifylist = []
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         # Set expected values
@@ -577,7 +579,9 @@ class TestUserList(TestUser):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         # Set expected values
@@ -602,7 +606,9 @@ class TestUserList(TestUser):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         # Set expected values
@@ -627,7 +633,9 @@ class TestUserList(TestUser):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         # Set expected values
@@ -672,7 +680,9 @@ class TestUserList(TestUser):
         ]
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        # DisplayCommandBase.take_action() returns two tuples
+        # In base command class Lister in cliff, abstract method take_action()
+        # returns a tuple containing the column names and an iterable
+        # containing the data to be listed.
         columns, data = self.cmd.take_action(parsed_args)
 
         kwargs = {