Returns a base directory in which to store user-specific application configuration information such as user preferences and settings.
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_CONFIG_HOME is defined.
XDG_CONFIG_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.