'this is for the vendor specific action
in_args is a dict,
svc is the IGD service,
the format is :
key is the argument name
value is a two element list, 1st one is the value of arguement, 2nd
is the UPnP data type defined in the spec. following is an example:
{\'NewPortMappingIndex\': [0, \'ui4\'],}'

def customAction(self, method_name, in_args={}, svc='WANIPConnection'):

    upnp_method = method_name
    sendArgs = dict(in_args)
    resp_xml = self.sendSOAP(self.pr.netloc, 'urn:schemas-upnp-org:service:{svc}:1'.format(svc=svc), self.ctrlURL, upnp_method, sendArgs)
    return resp_xml
