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L1·Foundations

✅Booleans & Truthiness

True, False, and what counts as 'truthy'.

booltruthyandornot

§ 1Falsy values

False, None, 0, 0.0, "", [], {}, (), set() — everything else is truthy.

§ 2Short-circuit

and returns the first falsy operand (or last). or returns the first truthy operand (or last). Not always a bool!

§ 3Chained comparisons

a < b < c is (a < b) and (b < c), evaluating b once.

Example

1print(bool([]))           # False​
2print(bool("0"))          # True (non-empty!)​
3print(0 or "default")     # 'default'​
4print(1 < 2 < 3)          # True​

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bool('False') is:
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