sequence homework // tricks inside

def adv_range(seq):
    for element in seq.split(','):
        if '-' in element:
            start, _, stop = element.partition('-')
            yield from range(int(start), int(stop)+1)
        else:
            yield int(element)

def safe_adv_range(seq, constructor=list):
    try:
        retval = constructor(adv_range(seq))
    except Exception as e:
        print(e)
        retval = constructor()
    return retval


seq = '1-5, 7, 9, 10-13'
result = safe_adv_range(seq)
sorted_result = sorted(result)

as_set = set(result)
# or
as_set = safe_adv_range(seq, set)


as_tuple = tuple(result)
# or
as_tuple = safe_adv_range(seq, tuple)


# super special trick to get a kind of a Ordered Set
# this works only since Python 3.6.
like_ordered_set = safe_adv_range(seq, dict.fromkeys).keys()

# pre Python3.6
like_ordered_set = safe_adv_range(seq, collections.OrderedDict.fromkeys).keys()