code: def get_region_size(region):
          
          if region is None:
              return 180.
          tokens = parse_hpxregion(region)
          if tokens[0] in ['DISK', 'DISK_INC']:
              return float(tokens[3])
          elif tokens[0] == 'HPX_PIXEL':
              pixel_size = get_pixel_size_from_nside(int(tokens[2]))
              return 2. * pixel_size
          else:
              raise Exception(
                  "HPX.get_region_size did not recognize region type %s" % tokens[0])
          return None
docs: Finds and returns the approximate size of region (in degrees)  
          from a HEALPix region string.