diff --git a/sdk/core/azure-core/azure/core/pipeline/transport/__init__.py b/sdk/core/azure-core/azure/core/pipeline/transport/__init__.py
index 03d5b0d19c88..7daa8fe4c959 100644
--- a/sdk/core/azure-core/azure/core/pipeline/transport/__init__.py
+++ b/sdk/core/azure-core/azure/core/pipeline/transport/__init__.py
@@ -24,137 +24,84 @@
 #
 # --------------------------------------------------------------------------
 
-import sys
 from ._base import HttpTransport, HttpRequest, HttpResponse
+from ._base_async import AsyncHttpTransport, AsyncHttpResponse
+
+# pylint: disable=undefined-all-variable
 
 __all__ = [
     'HttpTransport',
     'HttpRequest',
     'HttpResponse',
+    'RequestsTransport',
+    'RequestsTransportResponse',
+    'AsyncHttpTransport',
+    'AsyncHttpResponse',
+    'AsyncioRequestsTransport',
+    'AsyncioRequestsTransportResponse'
+    'TrioRequestsTransport',
+    'TrioRequestsTransportResponse',
+    'AioHttpTransport',
+    'AioHttpTransportResponse',
 ]
 
-# pylint: disable=unused-import, redefined-outer-name
-try:
-    from ._requests_basic import RequestsTransport, RequestsTransportResponse
-    __all__.extend([
-        'RequestsTransport',
-        'RequestsTransportResponse',
-    ])
-    try:
-        from ._base_async import AsyncHttpTransport, AsyncHttpResponse
-        from ._requests_asyncio import AsyncioRequestsTransport, AsyncioRequestsTransportResponse
-
-        __all__.extend([
-            'AsyncHttpTransport',
-            'AsyncHttpResponse',
-            'AsyncioRequestsTransport',
-            'AsyncioRequestsTransportResponse'
-        ])
-
-        if sys.version_info >= (3, 7):
-            __all__.extend([
-                'TrioRequestsTransport',
-                'TrioRequestsTransportResponse',
-                'AioHttpTransport',
-                'AioHttpTransportResponse',
-            ])
-
-            def __dir__():
-                return __all__
-
-            def __getattr__(name):
-                if name == 'AioHttpTransport':
-                    try:
-                        from ._aiohttp import AioHttpTransport
-                        return AioHttpTransport
-                    except ImportError:
-                        raise ImportError("aiohttp package is not installed")
-                if name == 'AioHttpTransportResponse':
-                    try:
-                        from ._aiohttp import AioHttpTransportResponse
-                        return AioHttpTransportResponse
-                    except ImportError:
-                        raise ImportError("aiohttp package is not installed")
-                if name == 'TrioRequestsTransport':
-                    try:
-                        from ._requests_trio import TrioRequestsTransport
-                        return TrioRequestsTransport
-                    except ImportError:
-                        raise ImportError("trio package is not installed")
-                if name == 'TrioRequestsTransportResponse':
-                    try:
-                        from ._requests_trio import TrioRequestsTransportResponse
-                        return TrioRequestsTransportResponse
-                    except ImportError:
-                        raise ImportError("trio package is not installed")
-                if name == '__bases__':
-                    raise AttributeError("module 'azure.core.pipeline.transport' has no attribute '__bases__'")
-                return name
-
-        else:
-            try:
-                from ._requests_trio import TrioRequestsTransport, TrioRequestsTransportResponse
-
-                __all__.extend([
-                    'TrioRequestsTransport',
-                    'TrioRequestsTransportResponse'
-                ])
-            except ImportError:
-                pass  # Trio not installed
-
-            try:
-                from ._aiohttp import AioHttpTransport, AioHttpTransportResponse
-
-                __all__.extend([
-                    'AioHttpTransport',
-                    'AioHttpTransportResponse',
-                ])
-            except ImportError:
-                pass  # Aiohttp not installed
-    except (ImportError, SyntaxError):
-        # requests library is installed but asynchronous pipelines not supported.
-        pass
-except (ImportError, SyntaxError):
-    # requests library is not installed
-    try:
-        from ._base_async import AsyncHttpTransport, AsyncHttpResponse
-        __all__.extend([
-            'AsyncHttpTransport',
-            'AsyncHttpResponse',
-        ])
-
-        if sys.version_info >= (3, 7):
-            __all__.extend([
-                'AioHttpTransport',
-                'AioHttpTransportResponse',
-            ])
-
-            def __dir__():
-                return __all__
+# pylint: disable=unused-import, redefined-outer-name, no-member, too-many-statements, too-many-branches
 
-            def __getattr__(name):
-                if name == 'AioHttpTransport':
-                    try:
-                        from ._aiohttp import AioHttpTransport
-                        return AioHttpTransport
-                    except ImportError:
-                        raise ImportError("aiohttp package is not installed")
-                if name == 'AioHttpTransportResponse':
-                    try:
-                        from ._aiohttp import AioHttpTransportResponse
-                        return AioHttpTransportResponse
-                    except ImportError:
-                        raise ImportError("aiohttp package is not installed")
-                return name
+def __dir__():
+    return __all__
 
-        else:
-            try:
-                from ._aiohttp import AioHttpTransport, AioHttpTransportResponse
-                __all__.extend([
-                    'AioHttpTransport',
-                    'AioHttpTransportResponse',
-                ])
-            except ImportError:
-                pass  # Aiohttp not installed
-    except (ImportError, SyntaxError):
-        pass  # Asynchronous pipelines not supported.
+def __getattr__(name):
+    transport = None
+    if name == 'AsyncioRequestsTransport':
+        try:
+            from ._requests_asyncio import AsyncioRequestsTransport
+            transport = AsyncioRequestsTransport
+        except ImportError:
+            raise ImportError("requests package is not installed")
+    if name == 'AsyncioRequestsTransportResponse':
+        try:
+            from ._requests_asyncio import AsyncioRequestsTransportResponse
+            transport = AsyncioRequestsTransportResponse
+        except ImportError:
+            raise ImportError("requests package is not installed")
+    if name == 'RequestsTransport':
+        try:
+            from ._requests_basic import RequestsTransport
+            transport = RequestsTransport
+        except ImportError:
+            raise ImportError("requests package is not installed")
+    if name == 'RequestsTransportResponse':
+        try:
+            from ._requests_basic import RequestsTransportResponse
+            transport = RequestsTransportResponse
+        except ImportError:
+            raise ImportError("requests package is not installed")
+    if name == 'AioHttpTransport':
+        try:
+            from ._aiohttp import AioHttpTransport
+            transport = AioHttpTransport
+        except ImportError:
+            raise ImportError("aiohttp package is not installed")
+    if name == 'AioHttpTransportResponse':
+        try:
+            from ._aiohttp import AioHttpTransportResponse
+            transport = AioHttpTransportResponse
+        except ImportError:
+            raise ImportError("aiohttp package is not installed")
+    if name == 'TrioRequestsTransport':
+        try:
+            from ._requests_trio import TrioRequestsTransport
+            transport = TrioRequestsTransport
+        except ImportError as ex:
+            if ex.msg.endswith("'requests'"):
+                raise ImportError("requests package is not installed")
+            raise ImportError("trio package is not installed")
+    if name == 'TrioRequestsTransportResponse':
+        try:
+            from ._requests_trio import TrioRequestsTransportResponse
+            transport = TrioRequestsTransportResponse
+        except ImportError:
+            raise ImportError("trio package is not installed")
+    if transport:
+        return transport
+    raise AttributeError(f"module 'azure.core.pipeline.transport' has no attribute {name}")