Skip to main content
← CoursesPython FoundationsModule 6 · Concurrency and parallelismMutable default args trapwrite117 / 170
💬 Discuss🧪 Playground+100 XP
Task
📝 **Task:** Rewrite this safely: \`def add(x, lst=None):\` — if lst is None, start fresh list; append x; return list. Print \`add(1)\` and \`add(2)\` on two lines. Expected:\n[1]\n[2] 📋 Edit the starter code below. Tests run automatically. 💡 **Hint:** Re-read the theory if you get stuck.

Keep going

✏️ Write your code here
🐍
Loading Python...
First visit only — ~5-10s. Stays cached afterward.
📊 Result
Press Run to see result...
📣 Help someone learn PythonShare this lesson with a friend — the first 15 are free, no signup.Tweet

💬 Discussion

Be the first to ask a question or share a tip.
Sign in to join the discussion. Reading is free.
Loading discussion…