Fix the timer never cleared — find the bug

function debounce(fn, delay) {
  return function (...args) {
    setTimeout(function () { fn(...args); }, delay);
  };
}
let calls = 0;
const debounced = debounce(function () { calls++; }, 10);
debounced();
debounced();
debounced();
setTimeout(function () {
  document.querySelector('#out').textContent = calls + " ran";
}, 30);