PHPSpec\Matcher\IterateAsMatcher::supports PHP Method

    public function supports($name, $subject, array $arguments)
    {
        return in_array($name, ['iterateAs', 'yield']) && 1 === count($arguments) && ($subject instanceof \Traversable || is_array($subject)) && ($arguments[0] instanceof \Traversable || is_array($arguments[0]));
    }