code: function penalizeUnderscoreValueCompare(a, b) {
          var aName = a.value.toLowerCase(), bName = b.value.toLowerCase();
          // this sort function will cause _ to sort lower than lower case
          // alphabetical letters
          if (aName[0] === "_" && bName[0] !== "_") {
              return 1;
          } else if (bName[0] === "_" && aName[0] !== "_") {
              return -1;
          }
          if (aName < bName) {
              return -1;
          } else if (aName > bName) {
              return 1;
          }
          return 0;
      }
docs: Comparison function used for sorting that does a case-insensitive string comparison on the "value" field of both objects. Unlike a normal string comparison, however, this sorts leading "_" to the bottom, given that a leading "_" usually denotes a private value.