code: def connect(self, source, target, witnesses):
          
          # print("Adding Edge: "+source+":"+target)
          if self.graph.has_edge(source, target):
              self.graph[source][target]["label"] += ", " + str(witnesses)
          else:
              self.graph.add_edge(source, target, label=witnesses)
docs: :type source: integer
          :type target: integer