code: def synchronize_simultaneous(self, node_ip):
          
  
          for candidate in self.factory.candidates[node_ip]:
              # Only if candidate is connected.
              if not candidate["con"].connected:
                  continue
  
              # Synchronise simultaneous node.
              if candidate["time"] -\
                      self.factory.nodes["simultaneous"][node_ip]["time"] >\
                      self.challege_timeout:
                  msg = "RECONNECT"
                  self.factory.nodes["simultaneous"][node_ip]["con"].\
                      send_line(msg)
                  return
  
          self.cleanup_candidates(node_ip)
          self.propogate_candidates(node_ip)
docs: Because adjacent mappings for certain NAT types can
          be stolen by other connections, the purpose of this
          function is to ensure the last connection by a passive
          simultaneous node is recent compared to the time for
          a candidate to increase the chance that the precited
          mappings remain active for the TCP hole punching
          attempt.