Recreating the jQuery animation speed syntax for CSS animations using LESS

gistfile1.sass

.animation-duration(@time) {
-webkit-animation-duration: @time;
   -moz-animation-duration: @time;
    -ms-animation-duration: @time;
     -o-animation-duration: @time;
        animation-duration: @time;
}

	.animation-duration(@time) when (@time = fast) {
	-webkit-animation-duration: 0.25s;
	   -moz-animation-duration: 0.25s;
	    -ms-animation-duration: 0.25s;
	     -o-animation-duration: 0.25s;
	        animation-duration: 0.25s;
	}
	
	.animation-duration(@time) when (@time = normal) {
	-webkit-animation-duration: 0.5s;
	   -moz-animation-duration: 0.5s;
	    -ms-animation-duration: 0.5s;
	     -o-animation-duration: 0.5s;
	        animation-duration: 0.5s;
	}
	
	.animation-duration(@time) when (@time = slow) {
	-webkit-animation-duration: 1s;
	   -moz-animation-duration: 1s;
	    -ms-animation-duration: 1s;
	     -o-animation-duration: 1s;
	        animation-duration: 1s;
	}