License: Your choice of MIT or Apache License 2.0

Python Sets are nice to work with, but very inefficient if you need a large set with mostly-consecutive integers. The RangeSet class provides efficient handling and storage for these sets.

RangeSet works with any class whose instances are

• comparable
• step-able, i.e. you can add 1 to them / subtract 1 from them.
• discrete, i.e. there is no value between n and n+1.

RangeSet doesn't add or subtract any other values, nor does it try to subtract two instances from each other.

The requirement to subtract 1 is an optimization that could be removed if necessary.