Stash\Pool::setItemClass PHP Method

    public function setItemClass($class)
    {
        if (!class_exists($class)) {
            throw new InvalidArgumentException('Item class ' . $class . ' does not exist');
        }
        $interfaces = class_implements($class, true);
        if (!in_array('Stash\\Interfaces\\ItemInterface', $interfaces)) {
            throw new \InvalidArgumentException('Item class ' . $class . ' must inherit from \\Stash\\Interfaces\\ItemInterface');
        }
        $this->itemClass = $class;
        return true;
    }

 protected function setUp()
 {
     $this->driver = new Ephemeral([]);
     $this->pool = new Pool();
     $this->pool->setDriver($this->driver);
     $this->pool->setItemClass('Bankiru\\Stash\\TaggedItem');
 }