function-weight-number-to-string

@function weight-number-to-string($weight)
{
    @if $weight == 100 { @return "ultra-light"; }
	@if $weight == 200 { @return "light"; }
	@if $weight == 300 { @return "book"; }
	@if $weight == 400 { @return "regular"; }
	@if $weight == 500 { @return "medium"; }
	@if $weight == 600 { @return "semi-bold"; }
	@if $weight == 700 { @return "bold"; }
	@if $weight == 800 { @return "extra-bold"; }
	@if $weight == 900 { @return "heavy"; }
	@else {
		@warn "Not a valid weight";
		@return false;
	}
}