@Override
	public Handle lexerCallCommand(GrammarAST ID, GrammarAST arg) {
		throw new UnsupportedOperationException("This element is not allowed in parsers.");
	}
{@code (BLOCK (ALT .))} or {@code (BLOCK (ALT 'a') (ALT .))}.
tool/src/org/antlr/v4/automata/ParserATNFactory.java