## Exporting CLASS Spectra through FITS

       1  set angle sec
       2  file in co21.30m
       3  find /range -2 2 -2 2
       4  get f
       5  set fits mode spectrum
       6  fits write single.fits
       7  find /range -2 2 -2 2
       8  fits write index.fits /mode index

1. Angles are expressed in arcseconds.
2. Open the .30m file.
3. Build the index.
4. Store the first spectrum in `R` memory.
5. Default mode for writing `FITS` is set to single spectrum.
6. Write the `R` memory in `FITS` format file 'single.fits'.
7. Re-build the index.
8. Write the whole index in `FITS` format file 'index.fits'.