///Returns first element of `$list`.
///@ignore Documentation: http://sassylists.com/documentation.html#sl-first
///@param {List} $list - list to retrieve first item from
///@throws Cannot find first item of empty list.
///@requires sl-is-empty
///@example
///		sl-first(a b c)
///		// a
///@example
///		sl-first(a)
///		// a
///@example
///		sl-first(())
///		// null
///
///@return {*}

@function sl-first($list) {
  @if sl-missing-dependencies(sl-is-empty) == true { @return null; }

  @if sl-is-empty($list) {
    @warn "Cannot find first item of empty list.";
    @return null;
  }

  @return nth($list, 1);
}

///@requires sl-first
///@alias sl-first
 
@function sl-head($list) {
  @return sl-first($list);
}