code: function(completedCount) {
  			if (completedCount > 0) {
  				moduleEl.querySelector('.completed-count').textContent = completedCount;
  				moduleEl.classList.add('has-completed-tasks');
  			} else {
  				moduleEl.classList.remove('has-completed-tasks');
  			}
  		}
docs: Updates the displayed count of completed tasks and hide/shows the button accordingly
  @param {number} completedCount # of completed tasks
  @returns {void}