code: def choose_coord_units(header):
      
      cunit = header['CUNIT1']
      match = re.match(r'^deg\s*$', cunit)
      if match:
          return 'degree'
  
      # raise WCSError("Don't understand units '%s'" % (cunit))
      return 'degree'
docs: Return the appropriate key code for the units value for the axes by
      examining the FITS header.