code: function toggleElements() {
          // convert arguments to array
          var args = Array.prototype.slice.call(arguments);
          args.forEach(function(buttonId) {
              var buttonEl = document.getElementById(buttonId);
              if (buttonEl) {
                  var curDisplayStyle = buttonEl.style.display;
                  buttonEl.style.display = curDisplayStyle === 'none' ? 'block' : 'none';
              }
          });
      }
docs: Helper function that toggles visibility of DOM elements with provided ids
  @param {String} variable number of elements' ids which visibility needs to be toggled