GML tweening

///turn(angle,target_angle,frames)
var dif=angle_difference(argument0,argument1);
if dif==0 {
    return 0;
}
return dif/argument2;
//idea is to return a value that, when added to angle every frame for "frames" frames, will result in target_angle.
//angle+angle_difference(angle,target_angle) should return target_angle, no?