code: function _keyLeft() {
              if (lxSelect.choicesViewMode !== 'panes' || lxSelect.panes.length < 2) {
                  return;
              }
  
              var previousPaneIndex = lxSelect.panes.length - 2;
  
              lxSelect.activeChoiceIndex = (
                  Object.keys(lxSelect.panes[previousPaneIndex]) || []
              ).indexOf(
                  (toggledPanes[previousPaneIndex] || {}).key
              );
  
              _closePane(previousPaneIndex);
          }
docs: When the left key is pressed and we are displaying the choices in pane mode, close the most right opened
  pane.