为什么Python2中的某些代码确定性和Python 3中的非确定性？

I'm trying to write a script to calculate all of the possible fuzzy string match matches to for a short string, or 'kmer', and the same code that works in Python 2.7.X gives me a non-deterministic answer with Python 3.3.X, and I can't figure out why.I'm trying to write a script to calculate all o