define([], function() {

  /** Used as a safe reference for `undefined` in pre-ES5 environments. */
  var undefined;

  /**
   * Checks if `value` is `undefined`.
   *
   * @static
   * @memberOf _
   * @category Lang
   * @param {*} value The value to check.
   * @returns {boolean} Returns `true` if `value` is `undefined`, else `false`.
   * @example
   *
   * _.isUndefined(void 0);
   * // => true
   *
   * _.isUndefined(null);
   * // => false
   */
  function isUndefined(value) {
    return value === undefined;
  }

  return isUndefined;
});