(n, iterable, padvalue=None)
return zip_longest(*[iter(iterable)]*n, fillvalue=padvalue)
grouper(3, 'abcdefg', 'x') --> ('a','b','c'), ('d','e','f'),
    ('g','x','x')
grouper(3, 'abcdefg', 'x') --> ('a','b','c'), ('d','e','f'),
    ('g','x','x')
grouper ( 3 abcdefg x ) -- > ( a b c ) ( d e f ) ( g x x )
def grouper(n, iterable, padvalue=None):
    '''grouper(3, 'abcdefg', 'x') --> ('a','b','c'), ('d','e','f'),
    ('g','x','x')'''
    return zip_longest(*[iter(iterable)]*n, fillvalue=padvalue)
def grouper ( n , iterable , padvalue = None ) : return zip_longest ( * [ iter ( iterable ) ] * n , fillvalue = padvalue )