docs: def startReceivingBoxes(self, sender):
          """
          Initialize route tracking objects.
          """
          self._sender = sender
          for routeName, route in self._unstarted.iteritems():
              # Any route which has been bound but which does not yet have a
              # remote route name should not yet be started.  These will be
              # started in Route.connectTo.
              if route.remoteRouteName is not _unspecified:
                  route.start()
          self._routes = self._unstarted
          self._unstarted = None