def iter_without(iterable, without=None):
    """
    Returns iterable without certain value

    >>> iter_without([1, None, 2, 3, None, 4])
    [1, 2, 3, 4]
    >>> iter_without(['a', 'x', 'b', 'c'], without='x')
    ['a', 'b', 'c']
    """
    return type(iterable)(
        i for i in iterable
        if i is not without
    )