tampermonkey @grant GM_setValue // @grant GM_getValue when i try open file

Question

// @grant        GM_setValue
// @grant        GM_getValue   

 let fileHandle;
            let fileData;
            let text

            async function read(){
                [fileHandle] = await window.showOpenFilePicker()
                fileData = await fileHandle.getFile();
                text = await fileData.text();
            }

            async function save(){

                let stream = await fileHandle.createWritable();
                var val= getValues();
                await stream.write(text+"\n"+val);
                await stream.close();
            }

how to open the file correctly so that I can simultaneously use // @provide GM_setValue // @provide GM_getValue