async function executeCode(code, lang) {
    const data = await fetch(
        window.location.protocol + '//' + window.location.hostname + '/exec',
        {
            method: 'POST',
            body: JSON.stringify({
                code,
                lang
            }),
            headers: {
                'Content-Type': 'application/json'
            }
        }
    )
    const out = await data.json();
    document.getElementById('output').innerHTML = out;
}