code: def _choose_random_edge(self, edges: Set[EDGE]) -> Optional[EDGE]:
          
          if edges:
              index = self._rand.randint(len(edges))
              for e in edges:
                  if not index:
                      return e
                  index -= 1
          return None
docs: Picks random edge from the set of edges.
  
          Args:
            edges: Set of edges to pick from.
  
          Returns:
            Random edge from the supplied set, or None for empty set.