TypeError: ‘zip’ object is not subscriptable

In Python 2, zip returned a list. In Python 3, zip returns an iterable object. But you can make it into a list just by calling list, as in:

list(zip(...))

In this case, that would be:

list(zip(*ngram))

With a list, you can use indexing:

items = list(zip(*ngram))
...
items[0]

etc.

But if you only need the first element, then you don’t strictly need a list. You could just use next.

In this case, that would be:

next(zip(*ngram))