code: def getContact(self, user=None, channel=None):
          
          try:
              return self.contacts[(channel, user)]
          except KeyError:
              new_contact = self.contactClass(self, user=user, channel=channel)
              self.contacts[(channel, user)] = new_contact
              new_contact.setServiceParent(self)
              return new_contact
docs: get a Contact instance for ``user`` on ``channel``