'Track start/stop token for subtree root created for a rule.
Only works with Tree nodes.  For rules that match nothing,
seems like this will yield start=i and stop=i-1 in a nil node.
Might be useful info so I\'ll not force to be i..i.'

def setTokenBoundaries(self, t, startToken, stopToken):

    if (t is None):
        return
    start = 0
    stop = 0
    if (startToken is not None):
        start = startToken.index
    if (stopToken is not None):
        stop = stopToken.index
    t.setTokenStartIndex(start)
    t.setTokenStopIndex(stop)
