utils.py 文件源码

def slice_arg(s):
    """
    Parse a string that describes a slice with start and end.

    >>> slice_arg('2:-3')
    slice(2, -3, None)

    >> slice_arg(':-3')
    slice(None, -3, None)

    >> slice_arg('2:')
    slice(2, None, None)
    """

    start, end = s.split(':')
    start = None if start == '' else int(start)
    end = None if end == '' else int(end)
    return slice(start, end)