function isNaN(value) {
	      // An `NaN` primitive is the only value that is not equal to itself.
	      // Perform the `toStringTag` check first to avoid errors with some host objects in IE.
	      return isNumber(value) && value != +value;
	    }
Checks if `value` is `NaN`.

**Note:** This method is not the same as [`isNaN`](https://es5.github.io/#x15.1.2.4)
which returns `true` for `undefined` and other non-numeric values.

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

_.isNaN(NaN);
// => true

_.isNaN(new Number(NaN));
// => true

isNaN(undefined);
// => true

_.isNaN(undefined);
// => false