Method SDL.Music()->fade_out()
- Method fade_out
 objectfade_out(intms)- Description
 Fades the music out over the given number of milliseconds.
After ms milliseconds have passed, the music will be stopped; i.e. playing() will return
0.- Parameter 
ms The number of milliseconds it will take to fade out the music, starting from now.
- Returns
 The SDL.Music object.