anchor.diff:          !    pop: main population on each site before (input) and after (output)
           !         annihilation.
    
  +        use spawn_data, only: spawn_t
  +
           type(spawn_t), intent(in)  :: spawn
           integer(int_p), intent(inout) :: pop(:,:)
   
  
positive.code:                     call simple_update_proj_energy(ref_det == idet, H0i, psip_list%pops(1,idet), qs, qs%estimators%proj_energy)
  
                      ! Attempt to spawn from each particle onto all connected determinants.
                      if (sparse_hamil) then
                          associate(hstart=>hamil_csr%row_ptr(idet), hend=>hamil_csr%row_ptr(idet+1)-1)
                              do ipart = 1, abs(psip_list%pops(1,idet))
                                  call attempt_spawn(rng, spawn, qs%tau, idet, &
  
negative.code: use const
  use dSFMT_interface
  use errors
  
  implicit none
  
  