Code snippet showing pure vs impure functions in Python

pure_vs_impure_functions.py

def strip_pure(sentence: str) -> str:
    return sentence.strip()


strip_impure_call_count = 0


def strip_impure(sentence: str) -> str:
    global strip_impure_call_count

    stripped_sentence = sentence.strip()

    # Side effect 1: modify global state
    strip_impure_call_count += 1
    # Side effect 2: output to stdout
    print(f"Called strip_impure {strip_call_count} times")

    return stripped_sentence