code: def visit(self, event):
          
          to_visit = False
          if event.arr_time_ut <= self.min_transfer_time+self.get_min_visit_time():
              to_visit = True
          else:
              for ve in self.visit_events:
                  if (event.trip_I == ve.trip_I) and event.arr_time_ut < ve.arr_time_ut:
                      to_visit = True
  
          if to_visit:
              self.visit_events.append(event)
              min_time = self.get_min_visit_time()
              # remove any visits that are 'too old'
              self.visit_events = [v for v in self.visit_events if v.arr_time_ut <= min_time+self.min_transfer_time]
          return to_visit
docs: Visit the stop if it has not been visited already by an event with
          earlier arr_time_ut (or with other trip that does not require a transfer)
  
          Parameters
          ----------
          event : Event
              an instance of the Event (namedtuple)
  
          Returns
          -------
          visited : bool
              if visit is stored, returns True, otherwise False