message: Make change suggested in Dylan's review.
diff: @@ -208,9 +208,7 @@ int main(int argc, char *argv[])
  // domain integrator.
  ParBilinearForm a(&fespace);
  if (pa) { a.SetAssemblyLevel(AssemblyLevel::PARTIAL); }
  -
  a.AddDomainIntegrator(new DiffusionIntegrator(one));
  - // a.AddDomainIntegrator(new MassIntegrator(one));
  // 12. Assemble the parallel bilinear form and the corresponding linear
  // system, applying any necessary transformations such as: parallel
  