def METHOD_NAME(self):
    """
    Return a list of usernames in the database.
    :rtype: list
    :returns: The usernames in the database.
    """
    if self.db == None:
        raise AssertionError("DB not open")
    self.lock.acquire()
    try:
        usernames = self.db.METHOD_NAME()
    finally:
        self.lock.release()
    usernames = [u for u in usernames if not u.startswith("--Reserved--")]
    return usernames