@classmethod
def get_user(cls, email=None, user_id=None):
    """ Return a dict for the user represented by the specified email
        or user_id.

        >>> user = Retaincc.get_user(user_id='123')
        >>> user['name']
        u'Somebody'

        """
    params = {'email': email, 'user_id': user_id}
    user_dict = cls._do_call('GET', cls.api_endpoint + 'users', params=params)
    return user_dict
