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Beginner · Write the code · from 50 Python Practice Problems with Instant Answer Checking (Beginner to Advanced)

From the lesson: 50 Python Practice Problems with Instant Answer Checking (Beginner to Advanced)

Fifty problems, each with a code editor and real tests. Write your solution, press Check, and see exactly which cases pass. Stuck? Hints reveal one at a time, and the solution unlocks once you have checked at least once. Your code and progress are saved in this browser.

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Write common(a, b) that returns the items found in both lists, in the order they appear in a, without duplicates.

common([1, 2, 3, 2, 4], [4, 2, 9])  ->  [2, 4]
def common(a, b):
pass
Solution unlocks after your first Check

What Check runs

Your code runs first, then each of these lines. The output must match exactly.

RunsExpected output
common([1, 2, 3, 2, 4], [4, 2, 9])[2, 4]
common(["x", "y"], ["z"])[]

More practice problems

All Python exercises · 50 practice problems