code: function defaultCompareKeysFunction (a, b) {
    if (a < b) { return -1; }
    if (a > b) { return 1; }
    if (a === b) { return 0; }
  
    var err = new Error("Couldn't compare elements");
    err.a = a;
    err.b = b;
    throw err;
  }
docs: /*
  Default compareKeys function will work for numbers, strings and dates