Function with default argument

Define a reusable greet helper with an optional prefix parameter.

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functions defaults basics

How it works

Default parameter values are evaluated once at function definition time — use immutable defaults like None for mutable types.

Callers can omit the argument to get sensible behavior or override it explicitly.

Keep defaults at the end of the parameter list; required args come first.

Python

def greet(name, prefix="Hello"):
    return f"{prefix}, {name}!"


print(greet("Python"))
print(greet("World", prefix="Hi"))