code: function(cache) {
      var tips = cache[""].tips;
  
      // Sort labels: metadata, then branch tips by first add,
      // then user entries by first add, then last run
      // Then return without metadata
      return Object.keys(cache)
        .sort(function(a, b) {
          var keys = Object.keys(cache);
  
          return (
            (a ? 1 : 0) - (b ? 1 : 0) ||
            (a in tips ? 0 : 1) - (b in tips ? 0 : 1) ||
            (a.charAt(0) === " " ? 1 : 0) - (b.charAt(0) === " " ? 1 : 0) ||
            keys.indexOf(a) - keys.indexOf(b)
          );
        })
        .slice(1);
    }
docs: Label sequence helper