nl_tokens: Adds a refinement on a hierarchical facet .
pl_tokens: function ( facet , <mask> ) { if ( this . isHierarchicalFacetRefined ( facet ) ) { throw new Error ( facet + ' is already refined.' ) ; } var mod = { } ; mod [ facet ] = [ path ] ; return this . setQueryParameters ( { hierarchicalFacetsRefinements : defaults ( { } , mod , this . hierarchicalFacetsRefinements ) } ) ; }