public function has(string $key): bool
    {
        return array_key_exists($key, $this->data) || array_key_exists($key, $this->session);
    }
public function has(string $key): bool
    {
        return array_key_exists($key, $this->data) || array_key_exists($key, $this->session);
    }
public function has ( string $ key ) : bool { return array_key_exists ( $ key , $ this -> data ) || array_key_exists ( $ key , $ this -> session ) ; }
Check if a key exists

@param string $key Key
@return boolean
Check if a key exists