Even 63-bit integers aren't (all) representable in IEEE double floating point values (that Python uses) which have a 53 bits mantissa.

For example, int(float(10¹⁸ - 1)) != 10¹⁸ - 1, but xrange(1, 10¹⁸) is perfectly valid (even in Python 2).

edit: how do I type two consecutive asterisks on Hacker News? Backslash doesn't seem to work as an escape character.

If you put two spaces at the beginning of a line, you'll get a monospaced "literal" mode.

  For example, int(float(10**18 - 1)) != 10**18 - 1,
  but xrange(1, 10**18) is perfectly valid (even in Python 2).

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Edit: failure. That's two stymied people :(