code: function hide() {
                // First things first: we don't show it anymore.
                ttScope.isOpen = false;
  
                //if tooltip is going to be shown after delay, we must cancel this
                $timeout.cancel( popupTimeout );
                popupTimeout = null;
  
                // And now we remove it from the DOM. However, if we have animation, we
                // need to wait for it to expire beforehand.
                // FIXME: this is a placeholder for a port of the transitions library.
                if ( ttScope.animation ) {
                  if (!transitionTimeout) {
                    transitionTimeout = $timeout(removeTooltip, 500);
                  }
                } else {
                  removeTooltip();
                }
              }
docs: Hide the tooltip popup element.