code: def graph_order(self):
          
          parentage = tuple(reversed(self.parentage))
          graph_order = []
          for i in range(len(parentage) - 1):
              parent, child = parentage[i : i + 2]
              graph_order.append(parent.index(child))
          return tuple(graph_order)
docs: Get graph-order tuple for node.
  
          ::
  
              >>> from uqbar.containers import UniqueTreeContainer, UniqueTreeNode
              >>> root_container = UniqueTreeContainer(name="root")
              >>> outer_container = UniqueTreeContainer(name="outer")
              >>> inner_container = UniqueTreeContainer(name="inner")
              >>> node_a = UniqueTreeNode(name="a")
              >>> node_b = UniqueTreeNode(name="b")
              >>> node_c = UniqueTreeNode(name="c")
              >>> node_d = UniqueTreeNode(name="d")
              >>> root_container.extend([node_a, outer_container])
              >>> outer_container.extend([inner_container, node_d])
              >>> inner_container.extend([node_b, node_c])
  
          ::
  
              >>> for node in root_container.depth_first():
              ...     print(node.name, node.graph_order)
              ...
              a (0,)
              outer (1,)
              inner (1, 0)
              b (1, 0, 0)
              c (1, 0, 1)
              d (1, 1)