///Tests whether `$list` has a single item.
///@ignore Documentation: http://sassylists.com/documentation.html#sl-is-single
///@param {List} $list - list to run test against
///@example
///		sl-is-single(())
///		// false
///@example
///		sl-is-single(a)
///		// true
///@example
///		sl-is-single(a b)
///		// false
///@return {Bool}
 
@function sl-is-single($list) {
  @return length($list) == 1;
}