'Iterates over the tags in the entire Sentence,
For example, Sentence.loop(POS, LEMMA) yields tuples of the part-of-speech tags and lemmata.
Possible tags: WORD, LEMMA, POS, CHUNK, PNP, RELATION, ROLE, ANCHOR or a custom word tag.
Any order or combination of tags can be supplied.'

def loop(self, *tags):

    for i in range(len(self.words)):
        (yield tuple([self.get(i, tag=tag) for tag in tags]))
