anchor.diff:                  spawned_walker_population = 0
   
                   ! Consider all walkers.
  -                spawndie: do iwalker = 1, ndets
  +                do iwalker = 1, ndets
   
                       ! Simulate spawning.
  -                    spawning: do ipart = 1, abs(walker_population(iwalker))
  +                    do ipart = 1, abs(walker_population(iwalker))
                           ! Attempt to spawn from the current particle onto all
                           ! connected determinants.
                           call attempt_spawn(iwalker)
  -                    end do spawning
  +                    end do
   
                       call simple_death(iwalker)
   
  -                end do spawndie
  +                end do
   
                   call simple_annihilation()
   
  
positive.code: 
      end subroutine simple_annihilation
  
  end module simple_fciqmc
  
negative.code:             ! Update the shift
              nparticles = sum(abs(walker_population))
              if (tVaryShift) then
                  call update_shift(nparticles_old, nparticles)
              end if
              nparticles_old = nparticles
              if (nparticles > target_particles) then
  