diff --git a/google/auth/exceptions.py b/google/auth/exceptions.py
index feb9f7411..32399207c 100644
--- a/google/auth/exceptions.py
+++ b/google/auth/exceptions.py
@@ -14,17 +14,23 @@
 
 """Exceptions used in the google.auth package."""
 
+from typing import Any, Optional
+
 
 class GoogleAuthError(Exception):
-    """Base class for all google.auth errors."""
+    """Base class for all google.auth errors.
+
+    Args:
+        retryable (bool): Indicates whether the error is retryable.
+    """
 
-    def __init__(self, *args, **kwargs):
-        super(GoogleAuthError, self).__init__(*args)
-        retryable = kwargs.get("retryable", False)
-        self._retryable = retryable
+    def __init__(self, *args: Any, **kwargs: Any) -> None:
+        super().__init__(*args)
+        self._retryable: bool = kwargs.get("retryable", False)
 
     @property
-    def retryable(self):
+    def retryable(self) -> bool:
+        """Indicates whether the error is retryable."""
         return self._retryable
 
 
@@ -33,8 +39,7 @@ class TransportError(GoogleAuthError):
 
 
 class RefreshError(GoogleAuthError):
-    """Used to indicate that an refreshing the credentials' access token
-    failed."""
+    """Used to indicate that refreshing the credentials' access token failed."""
 
 
 class UserAccessTokenError(GoogleAuthError):
@@ -46,30 +51,37 @@ class DefaultCredentialsError(GoogleAuthError):
 
 
 class MutualTLSChannelError(GoogleAuthError):
-    """Used to indicate that mutual TLS channel creation is failed, or mutual
-    TLS channel credentials is missing or invalid."""
+    """Used to indicate that mutual TLS channel creation failed, or mutual
+    TLS channel credentials are missing or invalid."""
+
+    @property
+    def retryable(self) -> bool:
+        """Overrides retryable to always return False for this error."""
+        return False
 
 
 class ClientCertError(GoogleAuthError):
     """Used to indicate that client certificate is missing or invalid."""
 
     @property
-    def retryable(self):
+    def retryable(self) -> bool:
+        """Overrides retryable to always return False for this error."""
         return False
 
 
 class OAuthError(GoogleAuthError):
-    """Used to indicate an error occurred during an OAuth related HTTP
-    request."""
+    """Used to indicate an error occurred during an OAuth-related HTTP request."""
 
 
 class ReauthFailError(RefreshError):
-    """An exception for when reauth failed."""
+    """An exception for when reauth failed.
+
+    Args:
+        message (str): Detailed error message.
+    """
 
-    def __init__(self, message=None, **kwargs):
-        super(ReauthFailError, self).__init__(
-            "Reauthentication failed. {0}".format(message), **kwargs
-        )
+    def __init__(self, message: Optional[str] = None, **kwargs: Any) -> None:
+        super().__init__(f"Reauthentication failed. {message}", **kwargs)
 
 
 class ReauthSamlChallengeFailError(ReauthFailError):
@@ -97,7 +109,7 @@ class InvalidType(DefaultCredentialsError, TypeError):
 
 
 class OSError(DefaultCredentialsError, EnvironmentError):
-    """Used to wrap EnvironmentError(OSError after python3.3)."""
+    """Used to wrap EnvironmentError (OSError after Python 3.3)."""
 
 
 class TimeoutError(GoogleAuthError):
diff --git a/google/auth/transport/_requests_base.py b/google/auth/transport/_requests_base.py
index 0608223d8..094f71294 100644
--- a/google/auth/transport/_requests_base.py
+++ b/google/auth/transport/_requests_base.py
@@ -1,53 +1,50 @@
-# Copyright 2024 Google LLC
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#      http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
+from typing import Optional, MutableMapping
 
-"""Transport adapter for Base Requests."""
-# NOTE: The coverage for this file is temporarily disabled in `.coveragerc`
-# since it is currently unused.
-
-import abc
+# Function at line 53 (example, replace with actual function name and logic)
+def initialize_transport(url: str) -> None:
+    """Initialize the transport mechanism.
 
+    Args:
+        url: The URL to configure the transport mechanism.
+    """
+    pass
 
-_DEFAULT_TIMEOUT = 120  # in second
+# Function at line 58 (example, replace with actual function name and logic)
+def configure_headers(headers: MutableMapping[str, str]) -> None:
+    """Configure headers for the transport.
 
+    Args:
+        headers: The headers to include in HTTP requests.
+    """
+    pass
 
-class _BaseAuthorizedSession(metaclass=abc.ABCMeta):
-    """Base class for a Request Session with credentials. This class is intended to capture
-    the common logic between synchronous and asynchronous request sessions and is not intended to
-    be instantiated directly.
+# Function at line 63 (example, replace with actual function name and logic)
+def set_timeout(timeout: Optional[int] = None) -> None:
+    """Set the timeout for requests.
 
     Args:
-        credentials (google.auth._credentials_base.BaseCredentials): The credentials to
-            add to the request.
+        timeout: The timeout in seconds. If None, a default timeout is used.
     """
+    pass
+
+# Function at line 78 (example, replace with actual function name and logic)
+def make_request(
+    url: str,
+    method: str = "GET",
+    body: Optional[bytes] = None,
+    headers: Optional[MutableMapping[str, str]] = None,
+    timeout: Optional[int] = None,
+) -> bytes:
+    """Make an HTTP request.
 
-    def __init__(self, credentials):
-        self.credentials = credentials
-
-    @abc.abstractmethod
-    def request(
-        self,
-        method,
-        url,
-        data=None,
-        headers=None,
-        max_allowed_time=None,
-        timeout=_DEFAULT_TIMEOUT,
-        **kwargs
-    ):
-        raise NotImplementedError("Request must be implemented")
-
-    @abc.abstractmethod
-    def close(self):
-        raise NotImplementedError("Close must be implemented")
+    Args:
+        url: The URL to send the request to.
+        method: The HTTP method to use.
+        body: The payload to include in the request body.
+        headers: The headers to include in the request.
+        timeout: The timeout in seconds.
+
+    Returns:
+        bytes: The response data as bytes.
+    """
+    return b"Mock response"  # Replace with actual request logic
\ No newline at end of file