'Add the input state to all successors of the given node.
:param node:        The node whose successors\' input states will be touched.
:param input_state: The state that will be added to successors of the node.
:return:            None'

def _add_input_state(self, node, input_state):

    successors = self._graph_visitor.successors(node)
    for succ in successors:
        if (succ in self._state_map):
            self._state_map[succ] = self._merge_states(succ, *[self._state_map[succ], input_state])
        else:
            self._state_map[succ] = input_state
