switch( pat ) { case Apply( _, Tree[] args ): return TreeInfo.methSymbol( pat ).hashCode() + args.hashCode(); }
      public int hashCode() {            switch( this ) {            case DefaultLabel:                  return 0;            case SimpleLabel( Literal lit ):                  return lit.value.hashCode();            case TreeLabel( Tree pat ):                  return pat.hashCode();            case TypeLabel( Type type ):                  return type.hashCode();            default:                  return super.hashCode();            }      }