[nslocum]

After a little trial and error, it appears that Python caches the values in range(-5,257).

  > -6 + 0 is -6
  False
  > -5 + 0 is -5
  True
  > 256 + 0 is 256
  True
  > 257 + 0 is 257
  False

[wahnfrieden]

(CPython)