'Revisit a node in the future. As a result, the successors to this node will be revisited as well.
:param node: The node to revisit in the future.
:return:     None'

def revisit(self, node, include_self=True):

    successors = self.successors(node)
    if include_self:
        self._sorted_nodes.add(node)
    for succ in successors:
        self._sorted_nodes.add(succ)
    self._sorted_nodes = OrderedSet(sorted(self._sorted_nodes, key=(lambda n: self._node_to_index[n])))
