Though "when" the object is created isn't always so straightforward:

  >>> x = 257
  >>> y = 257
  >>> x is y
  False
  >>> def f():
  ...     x = 257
  ...     y = 257
  ...     return x is y
  ...
  >>> f()
  True

The lesson being that `is` is essentially meaningless for immutable objects, and to always use `==`.