setTool(antlr.Tool tool) In order to make it so existing subclasses don't break, we won't require
that the antlr.Tool instance be passed as a constructor element.
In order to make it so existing subclasses don't break, we won't require
that the antlr.Tool instance be passed as a constructor element. Instead,
the antlr.Tool instance should register itself via
ANTLRTokdefParser.initTool(antlr.Tool) throws: IllegalStateException - if a tool has already been registered since: 2.7.2