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Functions & basics

Reusable building blocks — parameters, returns, scope, and clear function design.

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Functions & basics easy

Write a Pure Function Without Side Effects in Python

Defines a pure function that adds one to a number without modifying external state.

pure functions side effects functions
Python 
def add_one(x: int) -> int:
    """Adds 1 to the input without modifying any external state."""
    return x + 1

if __name__ == "__main__":
    original = 5
    result = add_one(original)
    print(f"Original: {original}")
    print(f"Result: {result}")
    print(f"Original unchanged: {original}")
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