anchor.diff:                      call death_ptr(walker_data(1,idet), walker_population(1,idet), nparticles(1), ndeath)
   
                       ! Clone Hellmann--Feynman walkers from Hamiltonian walkers.
  -                    ! CHECK
  +                    ! TODO: CHECK
                       call stochastic_hf_cloning(walker_data(1,idet), walker_population(1,idet), &
                                                  walker_population(2,idet), nparticles(2))
   
  
positive.code: 
                          ! Attempt to spawn Hellmann--Feynman walkers from
                          ! Hamiltonian walkers.
                          ! Currently only using operators diagonal in the basis,
                          ! so this isn't possible.
                          call spawner_ptr(cdet, walker_population(1,idet), nspawned, connection)
                          ! Spawn if attempt was successful.
                          if (nspawned /= 0) call create_spawned_particle(cdet, connection, nspawned, spawned_hf_pop)
  
negative.code:             ! t2-t1 is thus the time taken by this report loop.
              proj_hf_expectation = inst_proj_hf_t1 - proj_energy*D0_hf_population/D0_population
              if (parent) call write_fciqmc_report(ireport, nparticles_old(1), t2-t1)
              if (parent) then
                  ! DEBUG output only.
                  ! TODO: include with std. output.
                  write (17,*) ireport, inst_proj_hf_t1, hf_shift, nparticles_old, walker_population(:,1), &
                               D0_population, D0_hf_population
                  call flush(17)
              end if
  
              ! Write restart file if required.
              if (mod(ireport,write_restart_file_every_nreports) == 0) &
  