human
Solve the following python programming problem given the following code:
@command(('pl\\s+%s' % PL))
def plist(parturl):
assistant
#Here is the Python program you requested.

    """Retrieve YouTube playlist.
    """
    if (parturl in g.pafy_pls):
        (ytpl, plitems) = g.pafy_pls[parturl]
    else:
        util.dbg('%sFetching    playlist    using    pafy%s', c.y, c.w)
        ytpl = pafy.get_playlist2(parturl)
        plitems = util.IterSlicer(ytpl)
        g.pafy_pls[parturl] = (ytpl, plitems)
    def pl_seg(s, e):
        return [Video(i.videoid, i.title, i.length) for i in plitems[s:e]]
    msg = ('Showing    YouTube    playlist    %s' % ((c.y + ytpl.title) + c.w))
    loadmsg = 'Retrieving    YouTube    playlist'
    paginatesongs(pl_seg, length=len(ytpl), msg=msg, loadmsg=loadmsg)