code: function toggleChoice(choice, evt) {
              if (lxSelect.multiple && !lxSelect.autocomplete && angular.isDefined(evt)) {
                  evt.stopPropagation();
              }
  
              if (lxSelect.areChoicesOpened() && lxSelect.multiple) {
                  var dropdownElement = angular.element(angular.element(evt.target).closest('.dropdown-menu--is-open')[0]);
                  // If the dropdown element is scrollable, fix the content div height to keep the current scroll state.
                  if (dropdownElement.scrollTop() > 0) {
                      var dropdownContentElement = angular.element(dropdownElement.find('.dropdown-menu__content')[0]);
                      var dropdownFilterElement = angular.element(dropdownContentElement.find('.lx-select-choices__filter')[0]);
  
                      var newHeight = dropdownContentElement.height();
                      newHeight -= (dropdownFilterElement.length) ? dropdownFilterElement.outerHeight() : 0;
  
                      var dropdownListElement = angular.element(dropdownContentElement.find('ul > div')[0]);
                      dropdownListElement.css('height', newHeight + 'px');
  
                      // This function is called when the ng-change attached to the filter input is called.
                      lxSelect.resetDropdownSize = function() {
                          dropdownListElement.css('height', 'auto');
                          lxSelect.resetDropdownSize = undefined;
                      }
                  }
              }
  
              if (lxSelect.multiple && isSelected(choice)) {
                  lxSelect.unselect(choice);
              } else {
                  lxSelect.select(choice);
              }
  
              if (lxSelect.autocomplete) {
                  lxSelect.activeChoiceIndex = -1;
                  lxSelect.filterModel = undefined;
              }
  
              if (lxSelect.autocomplete || (lxSelect.choicesViewMode === 'panes' && !lxSelect.multiple)) {
                  LxDropdownService.close('dropdown-' + lxSelect.uuid);
              }
          }
docs: Toggle the given choice. If it was selected, unselect it. If it wasn't selected, select it.
  
  @param {Object} choice The choice to toggle.
  @param {Event}  [evt]  The event that triggered the function.