define(['./isObject'], function(isObject) {

  /** `Object#toString` result references. */
  var funcTag = '[object Function]';

  /** Used for native method references. */
  var objectProto = Object.prototype;

  /**
   * Used to resolve the [`toStringTag`](http://ecma-international.org/ecma-262/6.0/#sec-object.prototype.tostring)
   * of values.
   */
  var objToString = objectProto.toString;

  /**
   * Checks if `value` is classified as a `Function` object.
   *
   * @static
   * @memberOf _
   * @category Lang
   * @param {*} value The value to check.
   * @returns {boolean} Returns `true` if `value` is correctly classified, else `false`.
   * @example
   *
   * _.isFunction(_);
   * // => true
   *
   * _.isFunction(/abc/);
   * // => false
   */
  function isFunction(value) {
    // The use of `Object#toString` avoids issues with the `typeof` operator
    // in older versions of Chrome and Safari which return 'function' for regexes
    // and Safari 8 which returns 'object' for typed array constructors.
    return isObject(value) && objToString.call(value) == funcTag;
  }

  return isFunction;
});