doc/themes/learn2/scss/nucleus/functions/_direction.scss

@function opposite-direction($dir) {
	@if $dir == 'left' {
		@return right;
	}
	@else if  $dir == 'right' {
		@return left;
	}
	@else if $dir == 'ltr' {
		@return rtl;
	}
	@else if $dir == 'rtl' {
		@return ltr;
	}
	@else if $dir == 'top' {
		@return bottom;
	}
	@else if $dir == 'bottom' {
		@return top;
	}
	@else {
		@warn "#{$dir} is not a direction! Make sure your direction is all lowercase!";
		@return false;
	}
}

@function named-direction($dir) {
	@if $dir == 'ltr' {
		@return left;
	}
	@else if $dir == 'rtl' {
		@return right;
	}
	@else {
		@warn "#{$dir} is not a valid HTML direction! Make sure you are using a valid HTML direction";
		@return false;
	}
}