Disjoint set data strutcture and their union

Python implemetation of Union of disjoint set data structures.
I was dissatisfied with other python implementations of Disjoint sets data-structures, so I implemented this class based on Competitive Programming book by Steven Halim and Felix Halim.

Testing

For testing I used a rather pecuilar approach, I used the test.py for solving a codeforces.com problem which tests it extensively.