code: def fetch(cls, id, incident=None, endpoint=None, *args, **kwargs):
          
          if incident is None and endpoint is None:
              raise InvalidArguments(incident, endpoint)
  
          if endpoint is None:
              iid = incident['id'] if isinstance(incident, Entity) else incident
              endpoint = 'incidents/{0}/alerts'.format(iid)
  
          return getattr(Entity, 'fetch').__func__(cls, id, endpoint=endpoint,
                                                   *args, **kwargs)
docs: Customize fetch because this is a nested resource.