This fades the sprite(s) specified by the colors in sprite_colors from its current state to the rgb-values in RGB and then returns the faded palette.
palette must be a length-256 sequence of length-3 sequences, specifying a palette.
sprite_colors is a returned sequence from get_sprite_colors() (if you want to fade more than one sprite at the time, you could use colors1 & colors2... etc.).
RGB must be a length-3 sequence, specifying the red, green and blue values of the color.
delay is a value specifying how fast/slow the fading should be done (3 is a good value). If you only want to change the palette sequence and not the hardware palette, you can use the constant no_fading.