function isPlainObject(value) {
      if (!isObjectLike(value) ||
          objectToString.call(value) != objectTag || isHostObject(value)) {
        return false;
      }
      var proto = getPrototype(value);
      if (proto === null) {
        return true;
      }
      var Ctor = hasOwnProperty.call(proto, 'constructor') && proto.constructor;
      return (typeof Ctor == 'function' &&
        Ctor instanceof Ctor && funcToString.call(Ctor) == objectCtorString);
    }
Checks if `value` is a plain object, that is, an object created by the
`Object` constructor or one with a `[[Prototype]]` of `null`.

@static
@memberOf _
@since 0.8.0
@category Lang
@param {*} value The value to check.
@returns {boolean} Returns `true` if `value` is a plain object,
 else `false`.
@example

function Foo() {
  this.a = 1;
}

_.isPlainObject(new Foo);
// => false

_.isPlainObject([1, 2, 3]);
// => false

_.isPlainObject({ 'x': 0, 'y': 0 });
// => true

_.isPlainObject(Object.create(null));
// => true