Can "None" be Reassigned in Python?

Starting with Python 2.4+, None cannot be reassigned:

# Python 2.4+
# SyntaxError: cannot assign to None
None = 'foo'

This guarantees that:

• It is truly a constant, and;
• All None references are always the same.

Please note that in versions of Python prior to 2.4, it is possible to reassign None.