Returns a base directory in which to store state files specific to particular user.
On UNIX platforms this is determined using the mechanisms described
XDG Base Directory Specification.
In this case the directory retrieved will be
On Windows it follows XDG Base Directory Specification if
XDG_STATE_HOME is defined.
XDG_STATE_HOME is undefined, the folder to use for local (as opposed
to roaming) application data is used instead. See the
Note that in this case on Windows it will be the same
The return value is cached and modifying it at runtime is not supported, as it’s not thread-safe to modify environment variables at runtime.