docs: def get_secure_channel(crt_file, key_file, port=50051):
      """Try to connect over a secure channel."""
  
      creds = grpc.ssl_channel_credentials(
          root_certificates=open(str(crt_file), 'rb').read(),
          private_key=open(str(key_file), 'rb').read(),
          certificate_chain=open(str(crt_file), 'rb').read())
  
      address = "{}:{}".format(socket.gethostname(), port)
      channel = grpc.secure_channel(address, creds)
      return channel