_data)) { return $this->_data[$key]; } else { return FALSE; } } public function set (string $key, $data) { $this->_data[$key] = $data; return $data; } public function delete (string $key) { unset($this->_data[$key]); return TRUE; } public function exsit (string $key) { return array_key_exists($key, $this->_data); } public function list () { return $this->_data; } public function empty () { $this->_data = []; return TRUE; } public function __toString () { return json_encode($this->_data); } }