utils.py 文件源码

def _in_pairs(iterable):
    # Creates iterator that iterates over the list in pairs:
    # for a, b in _in_pairs([0, 1, 2, 3, 4]):
    #     print(a, b)
    #
    # will print:
    # 0, 1
    # 2, 3
    # 4, None
    shared_iter = iter(iterable)
    # Note that zip_longest is a compat import that uses
    # the itertools izip_longest.  This creates an iterator,
    # this call below does _not_ immediately create the list
    # of pairs.
    return zip_longest(shared_iter, shared_iter)