IntervalSet.union and IntervalSet.intersection should accept Interval objects

[AlexandreDecan]

Right now, it's not possible to write closed(3,4) | closed(5,6) | closed(4,5). It results in a TypeError saying that Interval object is not iterable.

The current workaround is to wrap the Interval object into a IntervalSet, e.g. closed(3,4) | closed(5,6) | IntervalSet([closed(4,5)]) which is not very convenient.

A simple way to support the first notation could be to add:

other = IntervalSet([other]) if isinstance(other, Interval) else other

It could actually be a good idea to have Interval objects also supporting IntervalSet. In that case, an easy way could be to add:

if isinstance(other, IntervalSet):
  return other.union(self)

[intiocean]

Nice - I hadn't considered that use case - I'd be happy to merge a change with your first suggestion and a couple of tests @AlexandreDecan :)

[AlexandreDecan]

I'm sorry I didn't submit a PR for that. As I wanted interval arithmetic for Python asap, and as pyinter does not seem to be really maintained anymore, I created my own library (see https://github.com/AlexandreDecan/python-intervals).