'''
for k, v in data.items():
v.discard(k) # Ignore self dependencies
- extra_items_in_deps = reduce(set.union, data.values()) - set(data.keys())
+ extra_items_in_deps = reduce(set.union, data.values(), set()) - set(data.keys())
data.update(dict([(item, set()) for item in extra_items_in_deps]))
while True:
ordered = set(item for item,dep in data.items() if not dep)