@Override
	public Handle tokenRef(TerminalAST node) {
		ATNState left = newState(node);
		ATNState right = newState(node);
		int ttype = g.getTokenType(node.getText());
		left.addTransition(new AtomTransition(right, ttype));
		node.atnState = left;
		return new Handle(left, right);
	}
From label {@code A} build graph {@code o-A->o}.
tool/src/org/antlr/v4/automata/ParserATNFactory.java