def __verify_auth_params(username, password, access_token):
        """Verify that valid authentication parameters were passed to __init__"""

        if all(v is not None for v in [username, password, access_token]):
            raise ValueError('Cannot supply a username/password and a access token')

        if (username is None or password is None) and access_token is None:
            raise ValueError('Must supply a username/password or access token')