# janet 1.10.1
# note that os/cd does not appear to update PWD in the shell's environment.
(os/cwd) # => "/Users/cell/tmp"
(os/getenv "PWD") # => "/Users/cell/tmp"
(os/cd "/tmp") # => nil
(os/cwd) # => "/private/tmp" (on Apple, /tmp is actually /private/tmp)
(os/getenv "PWD") # => "/Users/cell/tmp"