'Move the input pointer to the next incoming token.  The stream
must become active with LT(1) available.  consume() simply
moves the input pointer so that LT(1) points at the next
input symbol. Consume at least one token.
Walk past any token not on the channel the parser is listening to.'

def consume(self):

    if (self.p < len(self.tokens)):
        self.p += 1
        self.p = self.skipOffTokenChannels(self.p)
