anchor.diff:      i=1
       call output_timer%start()
       call dataset%save_file(trim(file_name), i, domain%model_time)
  -    call surface_dataset%save_file("surface_"//trim(file_name), i, domain%model_time)
  +    ! call surface_dataset%save_file("surface_"//trim(file_name), i, domain%model_time)
       next_output = domain%model_time + options%parameters%output_dt
       call output_timer%stop()
       i = i + 1
  
positive.code:             endif
  
              call dataset%save_file(trim(file_name), i, next_output)
              call surface_dataset%save_file("surface_"//trim(file_name), i, domain%model_time)
  
              next_output = next_output + options%parameters%output_dt
  
  
negative.code:     type(domain_t)  :: domain
      type(boundary_t):: boundary
      type(output_t)  :: dataset
      ! type(output_t)  :: surface_dataset
      type(timer_t)   :: initialization_timer, total_timer, input_timer, output_timer, physics_timer
      type(Time_type) :: next_output
  
  