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Functions & basics

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

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Functions & basics easy

Cache expensive function with lru_cache in Python

Use functools.lru_cache to memoize an expensive recursive function and show the dramatic speedup on repeated calls.

lru_cache caching decorators
Python 
from functools import lru_cache
import time


@lru_cache(maxsize=128)
def expensive_operation(n):
    """Simulate an expensive Fibonacci-like calculation."""
    if n < 2:
        return n
    return expensive_operation(n - 1) + expensive_operation(n - 2)


if __name__ == "__main__":
    # First call (uncached) - take…
15 0 Open

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