Checking that episodes are numbered consecutively

        else:

            reporter.add(None, 'Episode {0} has badly-formatted filename', filename)

    # Check episode filename numbering.

    # Check for duplicate episode numbers.

    reporter.check(len(seen) == len(set(seen)),

                        None,

                        'Duplicate episode numbers {0} vs {1}',

                        sorted(seen), sorted(set(seen)))

    # Check that numbers are consecutive.

    seen = [int(s) for s in seen]

    seen.sort()

    reporter.check(all([i+1 == n for (i, n) in enumerate(seen)]),

    clean = True

    for i in range(len(seen) - 1):

        clean = clean and ((seen[i+1] - seen[i]) == 1)

    reporter.check(clean,

                   None,

                   'Missing or non-consecutive episode numbers {0}',

                   seen)