I modified more modules to use the new API. I'm not sure that using the API in modules is safe.

It's safe to use the API in functions which begins with trying to initialize the variable. In such case, if the variable is cleared, calling the function later initialize again the variable and it's fine.

When for module variables only initialized when the module is initialized, there is a risk that a module function tries to access a variable which has been cleared previously during Python shutdown.

See for example changes in the _datetime module.