code: function togglePane(evt, parentIndex, indexOrKey, selectLeaf) {
              selectLeaf = (angular.isUndefined(selectLeaf)) ? true : selectLeaf;
              var pane = lxSelect.choicesViewSize === 'large' ? lxSelect.panes[parentIndex] : lxSelect.openedPanes[parentIndex];
  
              if (angular.isUndefined(pane)) {
                  return;
              }
  
              var key = indexOrKey;
              if (angular.isObject(pane) && angular.isNumber(indexOrKey)) {
                  key = (Object.keys(pane) || [])[indexOrKey];
              }
  
              if (angular.isDefined(toggledPanes[parentIndex])) {
                  var previousKey = toggledPanes[parentIndex].key;
  
                  _closePane(parentIndex);
  
                  if (previousKey === key) {
                      return;
                  }
              }
  
              var isLeaf = lxSelect.isLeaf(pane[key]);
              if (isLeaf) {
                  if (selectLeaf) {
                      lxSelect.toggleChoice(pane[key], evt);
                  }
  
                  return;
              }
  
              _openPane(parentIndex, key, false);
          }
docs: Toggle a pane.
  
  @param {Event}         evt               The click event that led to toggle the pane.
  @param {number}        parentIndex       The index of the containing pane.
  @param {number|string} indexOrKey        The index or the name of the pane to toggle.
  @param {boolean}       [selectLeaf=true] Indicates if we want to select the choice if the pane to toggle is
  in fact a leaf.