A Python boolean is either `True` or `False`. Boolean values drive conditional tests in `if` statements and loops, but a condition need not be a boolean object: most Python objects can be tested directly. section 8.11 section 8.11.1
In a conditional test, these values count as false:
- `False`, `None`, and numeric zero, including `0.0` and `0+0j`. section 3.4.1 section 8.11.1
- Empty strings and containers: `""`, `[]`, `{}`, and `set()`. Nonempty strings and containers count as true. section 8.11.1
- Nonzero numbers count as true. Some objects, such as file and code objects, lack a sensible empty-or-zero interpretation and are best avoided as conditions. section 8.11.1
Comparisons such as `==` and `!=` produce boolean results. Use `in` or `not in` for membership, and `is` or `is not` to test whether references identify the same object. Combine tests with `and`, `or`, and `not`; use parentheses when a complex expression’s grouping might be unclear. section 8.11.2
A range test
`if 0 < x and x < 10:` can be written `if 0 < x < 10:`. Also, `x = False; not x` evaluates to `True`, while `True * 2` evaluates to `2`: booleans behave like `1` and `0` in arithmetic. section 8.11.2 section 3.2.1
[2] and [3, 4] [3, 4] #1 [] and 5 [] #2 [2] or [3, 4] [2] #2 [] or 5 5 #1 #1 The second element must be evaluated. #2 Only the first element needs to be evaluated.
The outputs show a subtle distinction: `and` and `or` return an operand, not necessarily `True` or `False`. Evaluation stops once an operand determines the result. section 8.11.2
