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Default argument

Parameter with a fallback value: `def f(x=10)`. Beware mutable defaults — `def f(xs=[])` is a classic trap.

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Related — Functions

FunctionNamed reusable block of code. Defined with `def`. First-class — you can pass fun*args, **kwargsCapture variable positional and keyword arguments. Lets a function accept any siLambdaAn anonymous one-line function: `lambda x: x*2`. Use for short callbacks; preferDecoratorA higher-order function that wraps another to add behavior — logging, caching, aClosureAn inner function that captures variables from its enclosing scope. The captured