return bimaps[(isign+1)>>1](l);
return l;
  operator()(const QDPExpr<RHS,OLattice<T1> > & l, int isign)    {//    fprintf(stderr,"BiDirectionalMap(QDPExpr<OLattice>,%d)\n",isign);      // For now, simply evaluate the expression and then do the map      return bimaps[(isign+1)>>1](l);    }