Shift a non-terminal and prepare for the next state.

def shift(self, next_state, token_type, value, lineno, column):
        """Shift a non-terminal and prepare for the next state."""
        dfa, state, node = self.stack[-1]
        new_node = Node(token_type, value, None, lineno, column)
        node.children.append(new_node)
        self.stack[-1] = (dfa, next_state, node)