code: def has_predecessor(self, graph, dest, orig, branch, turn, tick, *, forward=None):
          
          if forward is None:
              forward = self.db._forward
          return orig in self._get_origcache(graph, dest, branch, turn, tick, forward=forward)
docs: Return whether an edge connects the destination to the origin at the given time.
  
          Doesn't require the edge's index, which makes it slower than retrieving a
          particular edge.