anchor.diff:               ! If this is not the first interaction, and the user requested to
                ! use the MRW, do the MRW to get out of the optically thick region
   
  -             if(interactions > 1 .and. use_mrw) then
  +             if(use_mrw.and.interactions > 1) then
                   do mrw_steps=1,n_mrw_max
                      if(tau_inv_planck_to_closest_wall(p) > mrw_gamma) then
                         call grid_do_mrw(p)
  
positive.code:                 end if
               end if
  
               call random_exp(tau)
  
               ! Propagate the optical depth sampled
               call grid_integrate(p,tau,tau_achieved)
  
               if(p%reabsorbed) then
  
negative.code:     ! Optical depth to travel
      real(dp) :: tau
  
      ! REMOVE
      real(dp) :: tau_achieved
  
  