Wrong return type in docstring for auth.create_custom_token()

[crunk1]

Environment

• Operating System version: Win 10
• Firebase SDK version: firebase_admin 2.9.0
• Library version: 2.9.0
• Firebase Product: auth
• Python version: 3.6.4

Problem

def create_custom_token(uid, developer_claims=None, app=None):
    """Builds and signs a Firebase custom auth token.
    Args:
      uid: ID of the user for whom the token is created.
      developer_claims: A dictionary of claims to be included in the token
          (optional).
      app: An App instance (optional).
    Returns:
      string: A token minted from the input parameters.
    Raises:
      ValueError: If input parameters are invalid.
    """
    token_generator = _get_auth_service(app).token_generator
    return token_generator.create_custom_token(uid, developer_claims)

The docstring says it returns a string, but in python 3, this actually returns a bytes type. https://github.com/firebase/firebase-admin-python/blob/master/firebase_admin/auth.py#L745 returns bytes from jwt.encode