def METHOD_NAME(self, user, limit=0, offset=0, sort=None):
    """
    List API keys for a given user.
    :param user: The user whose keys to list.
    :type user: dict
    :param limit: Result limit.
    :param offset: Result offset.
    :param sort: The sort structure to pass to pymongo.
    :rtype: iterable of API keys for the user.
    """
    return self.find({
        'userId': user['_id']
    }, limit=limit, offset=offset, sort=sort)