code: function defaultComparator(a, b) {
      if (a == b) {
          return 0;
      } else if (a > b) {
          return 1;
      } else if (a < b) {
          return -1;
      } else {
          throw new Error("Unstable comparison: " + a + " compared to " + b);
      }
  }
docs: @see https://github.com/substack/node-sorted/blob/master/index.js
  
  @private
  @param {*} a
  @param {*} b
  @returns {Number}