def get_client_login_token_string(http_body):
  """Returns the token value for a ClientLoginToken.

  Reads the token from the server's response to a Client Login request and
  creates the token value string to use in requests.

  Args:
    http_body: str The body of the server's HTTP response to a Client Login
        request

  Returns:
    The token value string for a ClientLoginToken.
  """
  for response_line in http_body.splitlines():
    if response_line.startswith('Auth='):
      # Strip off the leading Auth= and return the Authorization value.
      return response_line[5:]
  return None