return Type();
    });
    addConversion([](stablehlo::TokenType token) {
      return vhlo::TokenV1Type::get(token.getContext());
    });
    addBuiltinToVhloConversions();

    addArgumentMaterialization(MaterializeIllegalCast);
    addSourceMaterialization(MaterializeIllegalCast);
    addTargetMaterialization(MaterializeIllegalCast);
  }

        return type;
      }
      return {};
    });
    addConversion([](mlir::stablehlo::TokenType token) -> mlir::Type {
      return mlir::vhlo::TokenV1Type::get(token.getContext());
    });
    addBuiltinToVhloConversions();
  }

  mlir::Attribute convertEncoding(mlir::Attribute attr) const final {
    // Must be VHLO encoding, or convertible to VHLO encoding.
    if (attr.getDialect().getNamespace() ==