message: add gko namespace
diff: @@ -113,7 +113,7 @@ int main(int argc, char *argv[])
  auto neg_one = gko::initialize<vec>({-1.0}, exec);
  auto res = gko::initialize<vec>({0.0}, exec);
  A->apply(gko::lend(one), gko::lend(x), gko::lend(neg_one), gko::lend(b));
  - b->compute_norm2(lend(res));
  + b->compute_norm2(gko::lend(res));
  std::cout << "Residual norm sqrt(r^T r): \n";
  write(std::cout, gko::lend(res));
  