diff --git a/.coveragerc b/.coveragerc
index 9c6959c2..e02b8f0e 100644
--- a/.coveragerc
+++ b/.coveragerc
@@ -2,7 +2,6 @@
 branch = True
 
 [report]
-fail_under = 100
 show_missing = True
 omit =
     google/analytics/admin/__init__.py
diff --git a/.github/.OwlBot.lock.yaml b/.github/.OwlBot.lock.yaml
index da616c91..0954585f 100644
--- a/.github/.OwlBot.lock.yaml
+++ b/.github/.OwlBot.lock.yaml
@@ -1,3 +1,3 @@
 docker:
   image: gcr.io/repo-automation-bots/owlbot-python:latest
-  digest: sha256:c66ba3c8d7bc8566f47df841f98cd0097b28fff0b1864c86f5817f4c8c3e8600
+  digest: sha256:df50e8d462f86d6bcb42f27ecad55bb12c404f1c65de9c6fe4c4d25120080bd6
diff --git a/.kokoro/docs/common.cfg b/.kokoro/docs/common.cfg
index ce443c13..461fe9cc 100644
--- a/.kokoro/docs/common.cfg
+++ b/.kokoro/docs/common.cfg
@@ -30,7 +30,7 @@ env_vars: {
 
 env_vars: {
     key: "V2_STAGING_BUCKET"
-    value: "docs-staging-v2"
+    value: "docs-staging-v2-staging"
 }
 
 # It will upload the docker image after successful builds.
diff --git a/.kokoro/samples/python3.9/common.cfg b/.kokoro/samples/python3.9/common.cfg
new file mode 100644
index 00000000..3b7ebe8f
--- /dev/null
+++ b/.kokoro/samples/python3.9/common.cfg
@@ -0,0 +1,40 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+# Build logs will be here
+action {
+  define_artifacts {
+    regex: "**/*sponge_log.xml"
+  }
+}
+
+# Specify which tests to run
+env_vars: {
+    key: "RUN_TESTS_SESSION"
+    value: "py-3.9"
+}
+
+# Declare build specific Cloud project.
+env_vars: {
+    key: "BUILD_SPECIFIC_GCLOUD_PROJECT"
+    value: "python-docs-samples-tests-py39"
+}
+
+env_vars: {
+    key: "TRAMPOLINE_BUILD_FILE"
+    value: "github/python-analytics-admin/.kokoro/test-samples.sh"
+}
+
+# Configure the docker image for kokoro-trampoline.
+env_vars: {
+    key: "TRAMPOLINE_IMAGE"
+    value: "gcr.io/cloud-devrel-kokoro-resources/python-samples-testing-docker"
+}
+
+# Download secrets for samples
+gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/python-docs-samples"
+
+# Download trampoline resources.
+gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/trampoline"
+
+# Use the trampoline script to run in docker.
+build_file: "python-analytics-admin/.kokoro/trampoline.sh"
\ No newline at end of file
diff --git a/.kokoro/samples/python3.9/continuous.cfg b/.kokoro/samples/python3.9/continuous.cfg
new file mode 100644
index 00000000..a1c8d975
--- /dev/null
+++ b/.kokoro/samples/python3.9/continuous.cfg
@@ -0,0 +1,6 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "True"
+}
\ No newline at end of file
diff --git a/.kokoro/samples/python3.9/periodic-head.cfg b/.kokoro/samples/python3.9/periodic-head.cfg
new file mode 100644
index 00000000..f9cfcd33
--- /dev/null
+++ b/.kokoro/samples/python3.9/periodic-head.cfg
@@ -0,0 +1,11 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "True"
+}
+
+env_vars: {
+    key: "TRAMPOLINE_BUILD_FILE"
+    value: "github/python-pubsub/.kokoro/test-samples-against-head.sh"
+}
diff --git a/.kokoro/samples/python3.9/periodic.cfg b/.kokoro/samples/python3.9/periodic.cfg
new file mode 100644
index 00000000..50fec964
--- /dev/null
+++ b/.kokoro/samples/python3.9/periodic.cfg
@@ -0,0 +1,6 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "False"
+}
\ No newline at end of file
diff --git a/.kokoro/samples/python3.9/presubmit.cfg b/.kokoro/samples/python3.9/presubmit.cfg
new file mode 100644
index 00000000..a1c8d975
--- /dev/null
+++ b/.kokoro/samples/python3.9/presubmit.cfg
@@ -0,0 +1,6 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "True"
+}
\ No newline at end of file
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 4f00c7cf..62eb5a77 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -16,7 +16,7 @@
 # See https://pre-commit.com/hooks.html for more hooks
 repos:
 -   repo: https://github.com/pre-commit/pre-commit-hooks
-    rev: v3.4.0
+    rev: v4.0.1
     hooks:
     -   id: trailing-whitespace
     -   id: end-of-file-fixer
diff --git a/CHANGELOG.md b/CHANGELOG.md
index c676f90f..303d2629 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,17 @@
 # Changelog
 
+## [0.4.0](https://www.github.com/googleapis/python-analytics-admin/compare/v0.3.2...v0.4.0) (2021-06-23)
+
+
+### Features
+
+* add always_use_jwt_access ([#89](https://www.github.com/googleapis/python-analytics-admin/issues/89)) ([268fdec](https://www.github.com/googleapis/python-analytics-admin/commit/268fdec4dd859a42d1025f94812053311df149ce))
+
+
+### Documentation
+
+* omit mention of Python 2.7 in 'CONTRIBUTING.rst' ([#1127](https://www.github.com/googleapis/python-analytics-admin/issues/1127)) ([#84](https://www.github.com/googleapis/python-analytics-admin/issues/84)) ([6ce863e](https://www.github.com/googleapis/python-analytics-admin/commit/6ce863e147dae3c1da40c27034a0ac42180c6303)), closes [#1126](https://www.github.com/googleapis/python-analytics-admin/issues/1126)
+
 ### [0.3.2](https://www.github.com/googleapis/python-analytics-admin/compare/v0.3.1...v0.3.2) (2021-06-16)
 
 
diff --git a/CONTRIBUTING.rst b/CONTRIBUTING.rst
index 2cd4fe5f..8c22ca30 100644
--- a/CONTRIBUTING.rst
+++ b/CONTRIBUTING.rst
@@ -69,7 +69,6 @@ We use `nox <https://nox.readthedocs.io/en/latest/>`__ to instrument our tests.
 
 - To test your changes, run unit tests with ``nox``::
 
-    $ nox -s unit-2.7
     $ nox -s unit-3.8
     $ ...
 
@@ -144,7 +143,6 @@ Running System Tests
 
    # Run all system tests
    $ nox -s system-3.8
-   $ nox -s system-2.7
 
    # Run a single system test
    $ nox -s system-3.8 -- -k <name of test>
@@ -152,9 +150,8 @@ Running System Tests
 
   .. note::
 
-      System tests are only configured to run under Python 2.7 and
-      Python 3.8. For expediency, we do not run them in older versions
-      of Python 3.
+      System tests are only configured to run under Python 3.8.
+      For expediency, we do not run them in older versions of Python 3.
 
   This alone will not run the tests. You'll need to change some local
   auth settings and change some configuration in your project to
diff --git a/docs/conf.py b/docs/conf.py
index c886377e..d93bbc97 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -80,9 +80,9 @@
 master_doc = "index"
 
 # General information about the project.
-project = u"google-analytics-admin"
-copyright = u"2019, Google"
-author = u"Google APIs"
+project = "google-analytics-admin"
+copyright = "2019, Google"
+author = "Google APIs"
 
 # The version info for the project you're documenting, acts as replacement for
 # |version| and |release|, also used in various other places throughout the
@@ -281,7 +281,7 @@
     (
         master_doc,
         "google-analytics-admin.tex",
-        u"google-analytics-admin Documentation",
+        "google-analytics-admin Documentation",
         author,
         "manual",
     )
@@ -316,7 +316,7 @@
     (
         master_doc,
         "google-analytics-admin",
-        u"google-analytics-admin Documentation",
+        "google-analytics-admin Documentation",
         [author],
         1,
     )
@@ -335,7 +335,7 @@
     (
         master_doc,
         "google-analytics-admin",
-        u"google-analytics-admin Documentation",
+        "google-analytics-admin Documentation",
         author,
         "google-analytics-admin",
         "google-analytics-admin Library",
diff --git a/google/analytics/admin_v1alpha/services/analytics_admin_service/transports/base.py b/google/analytics/admin_v1alpha/services/analytics_admin_service/transports/base.py
index 90c401be..7538d3c0 100644
--- a/google/analytics/admin_v1alpha/services/analytics_admin_service/transports/base.py
+++ b/google/analytics/admin_v1alpha/services/analytics_admin_service/transports/base.py
@@ -24,6 +24,7 @@
 from google.api_core import gapic_v1  # type: ignore
 from google.api_core import retry as retries  # type: ignore
 from google.auth import credentials as ga_credentials  # type: ignore
+from google.oauth2 import service_account  # type: ignore
 
 from google.analytics.admin_v1alpha.types import analytics_admin
 from google.analytics.admin_v1alpha.types import resources
@@ -45,8 +46,6 @@
     except pkg_resources.DistributionNotFound:  # pragma: NO COVER
         _GOOGLE_AUTH_VERSION = None
 
-_API_CORE_VERSION = google.api_core.__version__
-
 
 class AnalyticsAdminServiceTransport(abc.ABC):
     """Abstract transport class for AnalyticsAdminService."""
@@ -69,6 +68,7 @@ def __init__(
         scopes: Optional[Sequence[str]] = None,
         quota_project_id: Optional[str] = None,
         client_info: gapic_v1.client_info.ClientInfo = DEFAULT_CLIENT_INFO,
+        always_use_jwt_access: Optional[bool] = False,
         **kwargs,
     ) -> None:
         """Instantiate the transport.
@@ -92,6 +92,8 @@ def __init__(
                 API requests. If ``None``, then default info will be used.
                 Generally, you only need to set this if you're developing
                 your own client library.
+            always_use_jwt_access (Optional[bool]): Whether self signed JWT should
+                be used for service account credentials.
         """
         # Save the hostname. Default to port 443 (HTTPS) if none is specified.
         if ":" not in host:
@@ -120,13 +122,20 @@ def __init__(
                 **scopes_kwargs, quota_project_id=quota_project_id
             )
 
+        # If the credentials is service account credentials, then always try to use self signed JWT.
+        if (
+            always_use_jwt_access
+            and isinstance(credentials, service_account.Credentials)
+            and hasattr(service_account.Credentials, "with_always_use_jwt_access")
+        ):
+            credentials = credentials.with_always_use_jwt_access(True)
+
         # Save the credentials.
         self._credentials = credentials
 
-    # TODO(busunkim): These two class methods are in the base transport
+    # TODO(busunkim): This method is in the base transport
     # to avoid duplicating code across the transport classes. These functions
-    # should be deleted once the minimum required versions of google-api-core
-    # and google-auth are increased.
+    # should be deleted once the minimum required versions of google-auth is increased.
 
     # TODO: Remove this function once google-auth >= 1.25.0 is required
     @classmethod
@@ -147,27 +156,6 @@ def _get_scopes_kwargs(
 
         return scopes_kwargs
 
-    # TODO: Remove this function once google-api-core >= 1.26.0 is required
-    @classmethod
-    def _get_self_signed_jwt_kwargs(
-        cls, host: str, scopes: Optional[Sequence[str]]
-    ) -> Dict[str, Union[Optional[Sequence[str]], str]]:
-        """Returns kwargs to pass to grpc_helpers.create_channel depending on the google-api-core version"""
-
-        self_signed_jwt_kwargs: Dict[str, Union[Optional[Sequence[str]], str]] = {}
-
-        if _API_CORE_VERSION and (
-            packaging.version.parse(_API_CORE_VERSION)
-            >= packaging.version.parse("1.26.0")
-        ):
-            self_signed_jwt_kwargs["default_scopes"] = cls.AUTH_SCOPES
-            self_signed_jwt_kwargs["scopes"] = scopes
-            self_signed_jwt_kwargs["default_host"] = cls.DEFAULT_HOST
-        else:
-            self_signed_jwt_kwargs["scopes"] = scopes or cls.AUTH_SCOPES
-
-        return self_signed_jwt_kwargs
-
     def _prep_wrapped_messages(self, client_info):
         # Precompute the wrapped methods.
         self._wrapped_methods = {
diff --git a/google/analytics/admin_v1alpha/services/analytics_admin_service/transports/grpc.py b/google/analytics/admin_v1alpha/services/analytics_admin_service/transports/grpc.py
index 21859787..6f1b6a91 100644
--- a/google/analytics/admin_v1alpha/services/analytics_admin_service/transports/grpc.py
+++ b/google/analytics/admin_v1alpha/services/analytics_admin_service/transports/grpc.py
@@ -151,6 +151,7 @@ def __init__(
             scopes=scopes,
             quota_project_id=quota_project_id,
             client_info=client_info,
+            always_use_jwt_access=True,
         )
 
         if not self._grpc_channel:
@@ -206,14 +207,14 @@ def create_channel(
               and ``credentials_file`` are passed.
         """
 
-        self_signed_jwt_kwargs = cls._get_self_signed_jwt_kwargs(host, scopes)
-
         return grpc_helpers.create_channel(
             host,
             credentials=credentials,
             credentials_file=credentials_file,
             quota_project_id=quota_project_id,
-            **self_signed_jwt_kwargs,
+            default_scopes=cls.AUTH_SCOPES,
+            scopes=scopes,
+            default_host=cls.DEFAULT_HOST,
             **kwargs,
         )
 
diff --git a/google/analytics/admin_v1alpha/services/analytics_admin_service/transports/grpc_asyncio.py b/google/analytics/admin_v1alpha/services/analytics_admin_service/transports/grpc_asyncio.py
index de690c94..8e3bbf82 100644
--- a/google/analytics/admin_v1alpha/services/analytics_admin_service/transports/grpc_asyncio.py
+++ b/google/analytics/admin_v1alpha/services/analytics_admin_service/transports/grpc_asyncio.py
@@ -80,14 +80,14 @@ def create_channel(
             aio.Channel: A gRPC AsyncIO channel object.
         """
 
-        self_signed_jwt_kwargs = cls._get_self_signed_jwt_kwargs(host, scopes)
-
         return grpc_helpers_async.create_channel(
             host,
             credentials=credentials,
             credentials_file=credentials_file,
             quota_project_id=quota_project_id,
-            **self_signed_jwt_kwargs,
+            default_scopes=cls.AUTH_SCOPES,
+            scopes=scopes,
+            default_host=cls.DEFAULT_HOST,
             **kwargs,
         )
 
@@ -197,6 +197,7 @@ def __init__(
             scopes=scopes,
             quota_project_id=quota_project_id,
             client_info=client_info,
+            always_use_jwt_access=True,
         )
 
         if not self._grpc_channel:
diff --git a/owlbot.py b/owlbot.py
index b131a470..9930484f 100644
--- a/owlbot.py
+++ b/owlbot.py
@@ -33,7 +33,9 @@
 # ----------------------------------------------------------------------------
 templated_files = common.py_library(cov_level=98, microgenerator=True)
 s.move(
-    templated_files, excludes=[".coveragerc"]
+    templated_files, excludes=[
+        ".coveragerc"
+    ]
 )  # the microgenerator has a good coveragerc file
 
 # fix coverage statement
@@ -41,4 +43,11 @@
 '''["']--cov=google/cloud["'],''',
 '''"--cov=google.analytics",''')
 
+# Block pushing non-cloud libraries to Cloud RAD
+s.replace(
+    ".kokoro/docs/common.cfg",
+    r'value: "docs-staging-v2"',
+    r'value: "docs-staging-v2-staging"'
+)
+
 s.shell.run(["nox", "-s", "blacken"], hide_output=False)
diff --git a/samples/requirements.txt b/samples/requirements.txt
index 11e7e0fe..e408ea07 100644
--- a/samples/requirements.txt
+++ b/samples/requirements.txt
@@ -1,2 +1,2 @@
-google-analytics-admin==0.2.0
+google-analytics-admin==0.3.2
 google-auth-oauthlib==0.4.4
\ No newline at end of file
diff --git a/setup.py b/setup.py
index de61a183..1cd3b327 100644
--- a/setup.py
+++ b/setup.py
@@ -19,7 +19,7 @@
 import os
 import setuptools  # type: ignore
 
-version = "0.3.2"
+version = "0.4.0"
 
 package_root = os.path.abspath(os.path.dirname(__file__))
 
@@ -45,7 +45,7 @@
     platforms="Posix; MacOS X; Windows",
     include_package_data=True,
     install_requires=(
-        "google-api-core[grpc] >= 1.22.2, < 2.0.0dev",
+        "google-api-core[grpc] >= 1.26.0, <2.0.0dev",
         "proto-plus >= 1.4.0",
         "packaging >= 14.3",
     ),
diff --git a/testing/constraints-3.6.txt b/testing/constraints-3.6.txt
index 05a62e3a..1b1c1ae9 100644
--- a/testing/constraints-3.6.txt
+++ b/testing/constraints-3.6.txt
@@ -5,7 +5,7 @@
 #
 # e.g., if setup.py has "foo >= 1.14.0, < 2.0.0dev",
 # Then this file should have foo==1.14.0
-google-api-core==1.22.2
+google-api-core==1.26.0
 proto-plus==1.4.0
 packaging==14.3
 google-auth==1.24.0  # TODO: remove when google-auth>=1.25.0 is required through google-api-core
diff --git a/tests/unit/gapic/admin_v1alpha/test_analytics_admin_service.py b/tests/unit/gapic/admin_v1alpha/test_analytics_admin_service.py
index f83a2ed7..8ed45c01 100644
--- a/tests/unit/gapic/admin_v1alpha/test_analytics_admin_service.py
+++ b/tests/unit/gapic/admin_v1alpha/test_analytics_admin_service.py
@@ -32,9 +32,6 @@
 )
 from google.analytics.admin_v1alpha.services.analytics_admin_service import pagers
 from google.analytics.admin_v1alpha.services.analytics_admin_service import transports
-from google.analytics.admin_v1alpha.services.analytics_admin_service.transports.base import (
-    _API_CORE_VERSION,
-)
 from google.analytics.admin_v1alpha.services.analytics_admin_service.transports.base import (
     _GOOGLE_AUTH_VERSION,
 )
@@ -54,8 +51,9 @@
 import google.auth
 
 
-# TODO(busunkim): Once google-api-core >= 1.26.0 is required:
-# - Delete all the api-core and auth "less than" test cases
+# TODO(busunkim): Once google-auth >= 1.25.0 is required transitively
+# through google-api-core:
+# - Delete the auth "less than" test cases
 # - Delete these pytest markers (Make the "greater than or equal to" tests the default).
 requires_google_auth_lt_1_25_0 = pytest.mark.skipif(
     packaging.version.parse(_GOOGLE_AUTH_VERSION) >= packaging.version.parse("1.25.0"),
@@ -66,16 +64,6 @@
     reason="This test requires google-auth >= 1.25.0",
 )
 
-requires_api_core_lt_1_26_0 = pytest.mark.skipif(
-    packaging.version.parse(_API_CORE_VERSION) >= packaging.version.parse("1.26.0"),
-    reason="This test requires google-api-core < 1.26.0",
-)
-
-requires_api_core_gte_1_26_0 = pytest.mark.skipif(
-    packaging.version.parse(_API_CORE_VERSION) < packaging.version.parse("1.26.0"),
-    reason="This test requires google-api-core >= 1.26.0",
-)
-
 
 def client_cert_source_callback():
     return b"cert bytes", b"key bytes"
@@ -139,6 +127,18 @@ def test_analytics_admin_service_client_from_service_account_info(client_class):
         assert client.transport._host == "analyticsadmin.googleapis.com:443"
 
 
+@pytest.mark.parametrize(
+    "client_class", [AnalyticsAdminServiceClient, AnalyticsAdminServiceAsyncClient,]
+)
+def test_analytics_admin_service_client_service_account_always_use_jwt(client_class):
+    with mock.patch.object(
+        service_account.Credentials, "with_always_use_jwt_access", create=True
+    ) as use_jwt:
+        creds = service_account.Credentials(None, None, None)
+        client = client_class(credentials=creds)
+        use_jwt.assert_called_with(True)
+
+
 @pytest.mark.parametrize(
     "client_class", [AnalyticsAdminServiceClient, AnalyticsAdminServiceAsyncClient,]
 )
@@ -18279,7 +18279,6 @@ def test_analytics_admin_service_transport_auth_adc_old_google_auth(transport_cl
         (transports.AnalyticsAdminServiceGrpcAsyncIOTransport, grpc_helpers_async),
     ],
 )
-@requires_api_core_gte_1_26_0
 def test_analytics_admin_service_transport_create_channel(
     transport_class, grpc_helpers
 ):
@@ -18315,84 +18314,6 @@ def test_analytics_admin_service_transport_create_channel(
         )
 
 
-@pytest.mark.parametrize(
-    "transport_class,grpc_helpers",
-    [
-        (transports.AnalyticsAdminServiceGrpcTransport, grpc_helpers),
-        (transports.AnalyticsAdminServiceGrpcAsyncIOTransport, grpc_helpers_async),
-    ],
-)
-@requires_api_core_lt_1_26_0
-def test_analytics_admin_service_transport_create_channel_old_api_core(
-    transport_class, grpc_helpers
-):
-    # If credentials and host are not provided, the transport class should use
-    # ADC credentials.
-    with mock.patch.object(
-        google.auth, "default", autospec=True
-    ) as adc, mock.patch.object(
-        grpc_helpers, "create_channel", autospec=True
-    ) as create_channel:
-        creds = ga_credentials.AnonymousCredentials()
-        adc.return_value = (creds, None)
-        transport_class(quota_project_id="octopus")
-
-        create_channel.assert_called_with(
-            "analyticsadmin.googleapis.com:443",
-            credentials=creds,
-            credentials_file=None,
-            quota_project_id="octopus",
-            scopes=(
-                "https://www.googleapis.com/auth/analytics.edit",
-                "https://www.googleapis.com/auth/analytics.manage.users",
-                "https://www.googleapis.com/auth/analytics.manage.users.readonly",
-                "https://www.googleapis.com/auth/analytics.readonly",
-            ),
-            ssl_credentials=None,
-            options=[
-                ("grpc.max_send_message_length", -1),
-                ("grpc.max_receive_message_length", -1),
-            ],
-        )
-
-
-@pytest.mark.parametrize(
-    "transport_class,grpc_helpers",
-    [
-        (transports.AnalyticsAdminServiceGrpcTransport, grpc_helpers),
-        (transports.AnalyticsAdminServiceGrpcAsyncIOTransport, grpc_helpers_async),
-    ],
-)
-@requires_api_core_lt_1_26_0
-def test_analytics_admin_service_transport_create_channel_user_scopes(
-    transport_class, grpc_helpers
-):
-    # If credentials and host are not provided, the transport class should use
-    # ADC credentials.
-    with mock.patch.object(
-        google.auth, "default", autospec=True
-    ) as adc, mock.patch.object(
-        grpc_helpers, "create_channel", autospec=True
-    ) as create_channel:
-        creds = ga_credentials.AnonymousCredentials()
-        adc.return_value = (creds, None)
-
-        transport_class(quota_project_id="octopus", scopes=["1", "2"])
-
-        create_channel.assert_called_with(
-            "analyticsadmin.googleapis.com:443",
-            credentials=creds,
-            credentials_file=None,
-            quota_project_id="octopus",
-            scopes=["1", "2"],
-            ssl_credentials=None,
-            options=[
-                ("grpc.max_send_message_length", -1),
-                ("grpc.max_receive_message_length", -1),
-            ],
-        )
-
-
 @pytest.mark.parametrize(
     "transport_class",
     [