public function exists($keyName = null, $lifetime = null)
    {
        return $this->uses()->exists($keyName, $lifetime);
    }
public function exists($keyName = null, $lifetime = null)
    {
        return $this->uses()->exists($keyName, $lifetime);
    }
public function exists ( $ keyName = null , $ lifetime = null ) { return $ this -> uses ( ) -> exists ( $ keyName , $ lifetime ) ; }
Checks if cache exists and it hasn't expired

@param string $keyName
@param int    $lifetime

@return boolean
Checks if cache exists and it hasn t expired