code: function isNative(value) {
    if (value == null) {
      return false;
    }
    if (objToString.call(value) == funcTag) {
      return reNative.test(fnToString.call(value));
    }
    return isObjectLike(value) && (isHostObject(value) ? reNative : reHostCtor).test(value);
  }
docs: Checks if `value` is a native function.
  
  @static
  @memberOf _
  @category Lang
  @param {*} value The value to check.
  @returns {boolean} Returns `true` if `value` is a native function, else `false`.
  @example
  
  _.isNative(Array.prototype.push);
  // => true
  
  _.isNative(_);
  // => false