Where do I find the python standard library code?

I wanted to try and look up the source of some of the modules in the Python standard library, but wasn't able to find them. I tried looking in the modules directory after downloading the python tarball, but it has mainly .c files. I also tried looking at the directory where the python that already comes with the OS (mac osx) has it's modules, and there it seems to have mainly .pyc and .pyo files. Would really appreciate it if someone can help me out.

(I tried what was suggested in the question How do I find the location of Python module sources? with no luck)

In cpython, many modules are implemented in C, and not in Python. You can find those in Modules/, whereas the pure Python ones reside in Lib/.

In some cases (for example the json module), the Python source code provides the module on its own and only uses the C module if it's available (to improve performance). For the remaining modules, you can have a look at PyPy's implementations.

The canonical repository for CPython is this Mercurial repository. There is also a git mirror on GitHub.