get title(){if(this.nested_level_===0){return'<root>';}
return this.title_;}
getSettingsKey(){if(this.name_===undefined){return undefined;}
const parentKey=this.parentContainer_.getSettingsKey();if(parentKey===undefined){return undefined;}
return parentKey+'.'+this.name_;}
push(slice){if(this.viewSubGroups_!==undefined){throw new Error('No new slices are allowed when view sub-groups already formed.');}