private static final IExpressionDescription convExpr(
     final Facet facet, final boolean label, final Set<Diagnostic> errors) {
   if (facet != null) {
     Expression expr = facet.getExpr();
     if (expr != null) {
       return label ? convertToLabel(expr, EGaml.getKeyOf(expr)) : convExpr(expr, errors);
     }
     String name = facet.getName();
     // TODO Verify the use of "facet"
     if (name != null) {
       return convertToLabel(null, name);
     }
   }
   return null;
 }