Heuristically computes and returns the region-specified ("default") culture for a given language. If the input culture is not neutral (i.e. it is region-specific), it is returned. Otherwise the method will find the region-qualified culture which most likely represents the culture's default/major region.

Heuristically computes and returns the region-specified ("default") culture code for a given language code. If the input culture is not neutral or does not have a region-qualified equivalent, null is returned.