This endpoint is used with a check that is of the TTL type. When this
    is called, the status of the check is set to warning and the TTL
    clock is reset.

    :param consul_url: The Consul server URL.
    :param checkid: The ID of the check to deregister from Consul.
    :param note: A human-readable message with the status of the check.
    :return: Boolean and message indicating success or failure.

    CLI Example:

    .. code-block:: bash

        salt '*' consul.agent_check_warn checkid='redis_check1' note='Forcing check into warning state.'

def agent_check_warn(consul_url=None, token=None, checkid=None, **kwargs):
    '''
    This endpoint is used with a check that is of the TTL type. When this
    is called, the status of the check is set to warning and the TTL
    clock is reset.

    :param consul_url: The Consul server URL.
    :param checkid: The ID of the check to deregister from Consul.
    :param note: A human-readable message with the status of the check.
    :return: Boolean and message indicating success or failure.

    CLI Example:

    .. code-block:: bash

        salt '*' consul.agent_check_warn checkid='redis_check1' note='Forcing check into warning state.'

    '''
    ret = {}
    query_params = {}
    if not consul_url:
        consul_url = _get_config()
        if not consul_url:
            log.error('No Consul URL found.')
            ret['message'] = 'No Consul URL found.'
            ret['res'] = False
            return ret

    if not checkid:
        raise SaltInvocationError('Required argument "checkid" is missing.')

    if 'note' in kwargs:
        query_params['note'] = kwargs['note']

    function = 'agent/check/warn/{0}'.format(checkid)
    res = _query(consul_url=consul_url,
                 function=function,
                 token=token,
                 query_params=query_params,
                 method='GET')
    if res['res']:
        ret['res'] = True
        ret['message'] = 'Check {0} marked as warning.'.format(checkid)
    else:
        ret['res'] = False
        ret['message'] = 'Unable to update check {0}.'.format(checkid)
    return ret