islice(iterable, stop) --> islice object
islice(iterable, start, stop[, step]) --> islice object
Return an iterator whose next() method returns selected values from an
iterable. If start is specified, will skip all preceding elements;
otherwise, start defaults to zero. Step defaults to one. If
specified as another value, step determines how many values are
skipped between successive calls. Works like a slice() on a list
but returns an iterator.