Time: 0:00
Test a custom input to verify an edge case (e.g. empty lists, negative numbers, duplicates).
This bug belongs to the mutation and copying bugs pattern
Assignment does not copy, a shallow copy still shares its contents, and mutating methods return None.
What went wrong: get(team, []) makes a new list but does not store it. The name is added to a list that is then thrown away.
The fix: teams.setdefault(team, []).append(name)
Remember: get() only reads. setdefault() reads, or stores the default if the key is missing.
The pattern behind it: mutation and copying bugs.
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<iframe src="https://trybughunt.com/embed/692c0efb-0404-4170-b63c-a2814d64104f" title="Debugging challenge: New team member vanishes from a new team" width="100%" height="580" loading="lazy" style="border:1px solid #d4d4d8;border-radius:12px;max-width:760px"></iframe>
<p style="font-size:14px">Debugging challenge from <a href="https://trybughunt.com/challenges/692c0efb-0404-4170-b63c-a2814d64104f">TryBugHunt</a></p>