code: def path(self):
          '''Path (list of nodes and actions) from root to this node.'''
          node = self
          path = []
          while node:
              path.append((node.action, node.state))
              node = node.parent
          return list(reversed(path)f path(self):
          '''Path (list of nodes and actions) from root to this node.'''
          node = self
          path = []
          while node:
              path.append((node.action, node.state))
              node = node.parent
          return list(reversed(path))
docs: Path (list of nodes and actions) from root to this node.