I'm looking for an implementation of the SHA-256 hash function written in Python. I want to use it to get a better understanding of how the SHA-256 function works, and I think Python is the ideal language for this. Pseudo-code has the limitation that I can't run/test it, to see what my modifications of the code do to the output.
PyPy's source contains a pure-python implementation of SHA-256 here. Poking around in that directory, you'll probably also find pure-python implementations of other standard hashes.