The documentation states that "*key*, *default* and the result are str." at https://github.com/python/cpython/blame/3.8/Doc/library/os.rst#L224 but either I'm missing something or it's not actually true:

$ python -c 'import os; print(type(os.getenv("FOO")))'           
<class 'NoneType'>
$ python -c 'import os; print(type(os.getenv("FOO", default=1)))'
<class 'int'>

Only *key* needs to be a string as it is used to lookup the value in os.environ.

I think this can be fixed by a new contributor

I consider a free type for the default as an implementation detail, not the encouraged approach.

Since the value is always a string, using the same type for the default sounds like a sane design for me.

I don't really have a preference regarding saying that `default` should be a string or not but the phrase should still be reworded to be less confusing.

In typeshed it's documented with a generic type: https://github.com/python/typeshed/blob/master/stdlib/3/os/__init__.pyi#L363.

It is not so uncommon to write:

    foo_rate = float(os.getenv("FOO_RATE", default_foo_rate))

where default_foo_rate is float.

In any case the default value for the default parameter is not a string.