code: def compute_pseudo_connections(transit_connections, start_time_dep,
                                 end_time_dep, transfer_margin,
                                 walk_network, walk_speed):
      
      # A pseudo-connection should be created after (each) arrival to a transit_connection's arrival stop.
      pseudo_connection_set = set()  # use a set to ignore possible duplicates
      for c in transit_connections:
          if start_time_dep <= c.departure_time <= end_time_dep:
              walk_arr_stop = c.departure_stop
              walk_arr_time = c.departure_time - transfer_margin
              for _, walk_dep_stop, data in walk_network.edges(nbunch=[walk_arr_stop], data=True):
                  walk_dep_time = walk_arr_time - data['d_walk'] / float(walk_speed)
                  if walk_dep_time > end_time_dep or walk_dep_time < start_time_dep:
                      continue
                  pseudo_connection = Connection(walk_dep_stop,
                                                 walk_arr_stop,
                                                 walk_dep_time,
                                                 walk_arr_time,
                                                 Connection.WALK_TRIP_ID,
                                                 Connection.WALK_SEQ,
                                                 is_walk=True)
                  pseudo_connection_set.add(pseudo_connection)
      return pseudo_connection_set
docs: Given a set of transit events and the static walk network,
      "transform" the static walking network into a set of "pseudo-connections".
  
      As a first approximation, we add pseudo-connections to depart after each arrival of a transit connection
      to it's arrival stop.
  
      Parameters
      ----------
      transit_connections: list[Connection]
      start_time_dep : int
          start time in unixtime seconds
      end_time_dep: int
          end time in unixtime seconds (no new connections will be scanned after this time)
      transfer_margin: int
          required extra margin required for transfers in seconds
      walk_speed: float
          walking speed between stops in meters / second
      walk_network: networkx.Graph
          each edge should have the walking distance as a data attribute ("d_walk") expressed in meters
  
      Returns
      -------
      pseudo_connections: set[Connection]