Time: 0:00
Test a custom input to verify an edge case (e.g. empty lists, negative numbers, duplicates).
This bug belongs to the type errors pattern
Totals that concatenate, sorts that put 10 before 9, comparisons that refuse to run.
What went wrong: The lowercase %y directive expects a two-digit year without century (e.g. '26'). Four-digit years require uppercase %Y.
The fix: Use uppercase %Y in strptime: datetime.strptime(date_str, '%Y-%m-%d')
Remember: In Python datetime formatting, %y represents two-digit years (00-99), while %Y represents four-digit years.
The pattern behind it: type errors.
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<iframe src="https://trybughunt.com/embed/b4059bf3-7620-4605-8b93-fb7e5f5d95a5" title="Debugging challenge: Four digit year string raises ValueError with lowercase y format" width="100%" height="580" loading="lazy" style="border:1px solid #d4d4d8;border-radius:12px;max-width:760px"></iframe>
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