incPy need checks the functions it caches to be pure and determinstic. determinstic function is a function that when given the same input , always returns the s

incPy need checks the functions it caches to be pure and determinstic. determinstic function is a function that when given the same input , always returns the same output. incPy tests for a few options of non-determinism , and will allow in the future to define non determinstic sources in a config file.