How to use PHPUnit assert methods in a Codeception functional test?

I'm using Codeception for unit, functional, and acceptance tests of my Laravel 4 PHP application. My unit tests look this: ``` use Codeception\Util\Stub; class ExampleTest extends \Codeception\TestCase\Test { public function testExample() { $example = true; $this->assertSame($example, true); } } ``` My functional tests look like this: ``` use \TestGuy; class ExampleCest { public function example(TestGuy $I) { $I->amOnPage('/auth/login'); $I->see('Sign in'); } } ``` But I also want to use PHPUnit assert methods in my functional tests. But when I try to, I get this error: Call to undefined method ExampleCest::assertSame() How do I use PHP assert methods in a Codeception functional test?