code: def secure_authorized_channel(
          credentials, request, target, ssl_credentials=None, **kwargs):
      
      # Create the metadata plugin for inserting the authorization header.
      metadata_plugin = AuthMetadataPlugin(credentials, request)
  
      # Create a set of grpc.CallCredentials using the metadata plugin.
      google_auth_credentials = grpc.metadata_call_credentials(metadata_plugin)
  
      if ssl_credentials is None:
          ssl_credentials = grpc.ssl_channel_credentials()
  
      # Combine the ssl credentials and the authorization credentials.
      composite_credentials = grpc.composite_channel_credentials(
          ssl_credentials, google_auth_credentials)
  
      return grpc.secure_channel(target, composite_credentials, **kwargs)
docs: Creates a secure authorized gRPC channel.
  
      This creates a channel with SSL and :class:`AuthMetadataPlugin`. This
      channel can be used to create a stub that can make authorized requests.
  
      Example::
  
          import google.auth
          import google.auth.transport.grpc
          import google.auth.transport.requests
          from google.cloud.speech.v1 import cloud_speech_pb2
  
          # Get credentials.
          credentials, _ = google.auth.default()
  
          # Get an HTTP request function to refresh credentials.
          request = google.auth.transport.requests.Request()
  
          # Create a channel.
          channel = google.auth.transport.grpc.secure_authorized_channel(
              credentials, 'speech.googleapis.com:443', request)
  
          # Use the channel to create a stub.
          cloud_speech.create_Speech_stub(channel)
  
      Args:
          credentials (google.auth.credentials.Credentials): The credentials to
              add to requests.
          request (google.auth.transport.Request): A HTTP transport request
              object used to refresh credentials as needed. Even though gRPC
              is a separate transport, there's no way to refresh the credentials
              without using a standard http transport.
          target (str): The host and port of the service.
          ssl_credentials (grpc.ChannelCredentials): Optional SSL channel
              credentials. This can be used to specify different certificates.
          kwargs: Additional arguments to pass to :func:`grpc.secure_channel`.
  
      Returns:
          grpc.Channel: The created gRPC channel.