<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def stats(args):
 """ %prog stats agpfile Print out a report for length of gaps and components. """

    from jcvi.utils.table import tabulate

    p = OptionParser(stats.__doc__)
    p.add_option("--warn", default=False, action="store_true",
                 help="Warnings on small component spans [default: %default]")
    opts, args = p.parse_args(args)

    if len(args) != 1:
        sys.exit(p.print_help())

    agpfile, = args

    agp = AGP(agpfile)
    gap_lengths = []
    component_lengths = []
    for a in agp:
        span = a.object_span
        if a.is_gap:
            label = a.gap_type
            gap_lengths.append((span, label))
        else:
            label = "{0}:{1}-{2}".format(a.component_id, a.component_beg, \
                   a.component_end)
            component_lengths.append((span, label))
            if opts.warn and span < 50:
                logging.error("component span too small ({0}):\n{1}".\
                    format(span, a))

    table = dict()
    for label, lengths in zip(("Gaps", "Components"),
            (gap_lengths, component_lengths)):

        if not lengths:
            table[(label, "Min")] = table[(label, "Max")] \
                                  = table[(label, "Sum")] = "n.a."
            continue

        table[(label, "Min")] = "{0} ({1})".format(*min(lengths))
        table[(label, "Max")] = "{0} ({1})".format(*max(lengths))
        table[(label, "Sum")] = sum(x[0] for x in lengths)

    print(tabulate(table), file=sys.stderr)