Simplified Contains
Definition of Superset via Subset
Slight aesthetic improvement
Another tiny stylistic change. Sets have elements, not keys.
Stylistic improvement in Union
Intersect entirely rewritten. Hopefully improved performance.
Style improvement in Difference.
Aesthetic improvement in SymmetricDifference
Simpler Clear
Stylistic improvement in Equal: No else after a return statement.
Merge pull request #2 from sjakobi/master

Beautification mostly