None on the left

A natural default, None is probably the most commonly assigned value in Python. But what happens if you move it to the left side of that equation?

In Python 2:

>>> None = 2
  File "<stdin>", line 1
SyntaxError: cannot assign to None

This is similar to what happens when you assign to a literal:

>>> 1 = 2
  File "<stdin>", line 1
SyntaxError: can't assign to literal

In Python 3 this walk on the wild side will get you a slightly different error:

>>> None = 1
  File "<stdin>", line 1
SyntaxError: can't assign to keyword

None has graduated from useful snowflake to full-blown keyword!