code: def wr_long(f, x):
      
      if PYTHON3:
          f.write(bytes([x        & 0xff]))
          f.write(bytes([(x >> 8)  & 0xff]))
          f.write(bytes([(x >> 16) & 0xff]))
          f.write(bytes([(x >> 24) & 0xff]))
      else:
          f.write(chr( x        & 0xff))
          f.write(chr((x >> 8)  & 0xff))
          f.write(chr((x >> 16) & 0xff))
          f.write(chr((x >> 24) & 0xff))
docs: Internal; write a 32-bit int to a file in little-endian order.