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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def agent_service_maintenance(consul_url=None, token=None, serviceid=None, **kwargs):
    '''
    Used to place a service into maintenance mode.

    :param consul_url: The Consul server URL.
    :param serviceid: A name of the service.
    :param enable: Whether the service should be enabled or disabled.
    :param reason: A human readable message of why the service was
                   enabled or disabled.
    :return: Boolean and message indicating success or failure.

    CLI Example:

    .. code-block:: bash

        salt '*' consul.agent_service_deregister serviceid='redis' enable='True' reason='Down for upgrade'

    '''
    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 serviceid:
        raise SaltInvocationError('Required argument "serviceid" is missing.')

    if 'enable' in kwargs:
        query_params['enable'] = kwargs['enable']
    else:
        ret['message'] = 'Required parameter "enable" is missing.'
        ret['res'] = False
        return ret

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

    function = 'agent/service/maintenance/{0}'.format(serviceid)
    res = _query(consul_url=consul_url,
                 token=token,
                 function=function,
                 query_params=query_params)

    if res['res']:
        ret['res'] = True
        ret['message'] = ('Service {0} set in '
                          'maintenance mode.'.format(serviceid))
    else:
        ret['res'] = False
        ret['message'] = ('Unable to set service '
                          '{0} to maintenance mode.'.format(serviceid))
    return ret