code: function baseSortedIndexBy(array, value, iteratee, retHighest) {
          value = iteratee(value);
          var low = 0, high = array ? array.length : 0, valIsNaN = value !== value, valIsNull = value === null, valIsUndef = value === undefined;
          while (low < high) {
            var mid = nativeFloor((low + high) / 2), computed = iteratee(array[mid]), isDef = computed !== undefined, isReflexive = computed === computed;
            if (valIsNaN) {
              var setLow = isReflexive || retHighest;
            } else if (valIsNull) {
              setLow = isReflexive && isDef && (retHighest || computed != null);
            } else if (valIsUndef) {
              setLow = isReflexive && (retHighest || isDef);
            } else if (computed == null) {
              setLow = false;
            } else {
              setLow = retHighest ? computed <= value : computed < value;
            }
            if (setLow) {
              low = mid + 1;
            } else {
              high = mid;
            }
          }
          return nativeMin(high, MAX_ARRAY_INDEX);
        }
docs: The base implementation of `_.sortedIndexBy` and `_.sortedLastIndexBy`
  which invokes `iteratee` for `value` and each element of `array` to compute
  their sort ranking. The iteratee is invoked with one argument; (value).
  
  @private
  @param {Array} array The sorted array to inspect.
  @param {*} value The value to evaluate.
  @param {Function} iteratee The iteratee invoked per element.
  @param {boolean} [retHighest] Specify returning the highest qualified index.
  @returns {number} Returns the index at which `value` should be inserted into `array`.