Cross-platform way to find the null device?

I want to redirect stderr to /dev/null on Unix, or nul on Windows. Is
there a simple way to find out the name of this machine's null device?
Python has "os.devnull" [1] but in Pike, what I'm looking at is a #if
__NT__ block. Is there a better way?

ChrisA

[1] https://docs.python.org/3/library/os.html#os.devnull