Retrieves the incident id/ids of the incident/incidents from the
        output response

        Returns:
            incident_id(namedtuple): List of named tuples of incident id/ids of
            the incident/incidents

def incident_id(self):
        """Retrieves the incident id/ids of the incident/incidents from the
        output response

        Returns:
            incident_id(namedtuple): List of named tuples of incident id/ids of
            the incident/incidents
        """
        resource_list = self.traffic_incident()
        incident_id = namedtuple('incident_id', 'incident_id')
        if len(resource_list) == 1 and resource_list[0] is None:
            return None
        else:
            try:
                return [incident_id(resource['incidentId'])
                        for resource in resource_list]
            except (KeyError, TypeError):
                return [incident_id(resource['IncidentId'])
                        for resource in resource_list]