Get the input abstract state for this node, and remove it from the state map.

        :param node: The node in graph.
        :return:     A merged state, or None if there is no input state for this node available.

def _pop_input_state(self, node):
        """
        Get the input abstract state for this node, and remove it from the state map.

        :param node: The node in graph.
        :return:     A merged state, or None if there is no input state for this node available.
        """

        if node in self._state_map:
            return self._state_map.pop(node)
        return None