'Match needs to return the current input symbol, which gets put
into the label for the associated token ref; e.g., x=ID.  Token
and tree parsers need to return different objects. Rather than test
for input stream type or change the IntStream interface, I use
a simple method to ask the recognizer to tell me what the current
input symbol is.
This is ignored for lexers.'

def getCurrentInputSymbol(self, input):

    return None
