def check_user(auth_user, request_handler=None):
    """
    Check logged user and return it's data.
    On error raise CheckUserError exception
    :param auth_user:
    :return: dict with user's data
    """
    res = {'id': auth_user.id, 'username': auth_user.username, 'first_name':
        auth_user.user.first_name, 'last_name': auth_user.user.last_name}
    return res
