Cache\Adapter\Common\CacheItem::__construct PHP Method

    public function __construct($key, $callable = null, $value = null)
    {
        $this->key = $key;
        if ($callable === true) {
            $this->hasValue = true;
            $this->value = $value;
        } elseif ($callable !== false) {
            // This must be a callable or null
            $this->callable = $callable;
        }
    }