Reference

ActivePython 2.5 documentation

3.2 Boolean Operations -- `and`, `or`, `not`

These are the Boolean operations, ordered by ascending priority:

Operation	Result	Notes
`x or y`	if `x` is false, then `y`, else `x`	(1)
`x and y`	if `x` is false, then `x`, else `y`	(1)
`not x`	if `x` is false, then `True`, else `False`	(2)

Notes:

(1): These only evaluate their second argument if needed for their outcome.
(2): "not" has a lower priority than non-Boolean operators, so not a == b is interpreted as not (a == b), and a == not b is a syntax error.

See About this document... for information on suggesting changes.