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def flatten(items):

Python · general · type the snippet below to practice

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This is the flatten snippet in Python — 9 lines of real Python code that exercises common patterns you'll see in production. DeveloperType scores you on net WPM and accuracy and only counts runs above 95% accuracy on the leaderboard, so practice rewards precision, not speed alone.

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def flatten(items):
    out = []
    for x in items:
        if isinstance(x, list):
            out.extend(flatten(x))
        else:
            out.append(x)
    return out

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