<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def check(args):
 """ Implement the 'greg check' command """

    session = c.Session(args)
    if str(args["url"]) != 'None':
        url = args["url"]
        name = "DEFAULT"
    else:
        try:
            url = session.feeds[args["feed"]]["url"]
            name = args["feed"]
        except KeyError:
            sys.exit("You don't appear to have a feed with that name.")
    podcast = aux.parse_podcast(url)
    for entry in enumerate(podcast.entries):
        listentry = list(entry)
        print(listentry[0], end=": ")
        try:
            print(listentry[1]["title"], end=" (")
        except:
            print(listentry[1]["link"], end=" (")
        try:
            print(listentry[1]["updated"], end=")")
        except:
            print("", end=")")
        print()
    dumpfilename = os.path.join(session.data_dir, 'feeddump')
    with open(dumpfilename, mode='wb') as dumpfile:
        dump = [name, podcast]
        pickle.dump(dump, dumpfile)