zip with trim/fill

zip_trim.py

def zip_trim(i1, i2, trim='shortest', default=None):
    ''' trim = 'shortest' | 'longest' | 'first' | 'second'
    '''
    i1_iter = iter(i1)
    i2_iter = iter(i2)
    while True:
        stop = False
        try:
            e1 = next(i1_iter)
        except StopIteration:
            if trim in ('shortest', 'first'):
                raise
            e1 = default
            stop = True
        try:
            e2 = next(i2_iter)
        except StopIteration:
            if trim in ('shortest', 'second') or stop:
                raise
            e2 = default
        yield e1, e2