examples/lists/sort_mixed.py
from __future__ import print_function

mixed = [100, 'foo', 42, 'bar']
print(mixed)
mixed.sort()
print(mixed)

In Python 2 puts the numbers first in numerical order and then the strings in ASCII order.

[100, 'foo', 42, 'bar']
[42, 100, 'bar', 'foo']

In Python 3 it throws an exception.

[100, 'foo', 42, 'bar']
Traceback (most recent call last):
  File "examples/lists/sort_mixed.py", line 5, in 
    mixed.sort()
TypeError: unorderable types: str() < int()