code: def quantity_to_hdf5(f, key, q):
      
  
      if hasattr(q, 'unit'):
          f[key] = q.value
          f[key].attrs['unit'] = str(q.unit)
  
      else:
          f[key] = q
          f[key].attrs['unit'] = ""
docs: Turn an Astropy Quantity object into something we can write out to
      an HDF5 file.
  
      Parameters
      ----------
      f : :class:`h5py.File`, :class:`h5py.Group`, :class:`h5py.DataSet`
      key : str
          The name.
      q : float, `astropy.units.Quantity`
          The quantity.