anchor.diff:    dimids =  (/ y_dimid, x_dimid /)
   
     ! Define the variable. 
  -  chunksizes = (/ 256, 256 /)
  +  chunksizes = (/ 256, 10 /)
     call handle_err(nf90_def_var(ncid, 'data', NF90_INT, dimids, & 
          varid, chunksizes = chunksizes, deflate_level = 4))
   
  
positive.code: 
    ! We are writing 2D data, a 6 x 12 grid. 
    integer, parameter :: MAX_DIMS = 2
    integer, parameter :: NX = 4096, NY = 4096
    integer :: data_out(NY, NX), data_in(NY, NX)
  
    ! We need these ids and other gunk for netcdf.
  
negative.code:   ! Check some stuff out.
    call handle_err(nf90_inquire(ncid, ndims, nvars, ngatts, unlimdimid, file_format))
    if (ndims /= 2 .or. nvars /= 1 .or. ngatts /= 0 .or. unlimdimid /= -1 .or. &
         file_format /= nf90_format_netcdf4_classic) stop 3
  
    call handle_err(nf90_inquire_variable(ncid, varid, name_in, xtype_in, ndims, dimids_in, &
         natts_in, contiguous_in, chunksizes_in, deflate_level_in, shuffle_in, fletcher32_in, &
  