Py2.6+ and Py3.0+ backport of Python 3.3's LRU Cache (Python recipe) by Raymond Hettinger Forked from Recipe 577970 (Full featured backport from Python 3.3. It passes the 3.3 test suite.) Full-featured O(1) LRU cache backported from Python3.3. The full Py3.3 API is supported (thread safety, maxsize, keyword args, type checking, __wrapped__, and cache_info). Includes Py3.3 optimizations for better