Code reviewHardcr-g504

Subject IdempotencyLevel Senior–Staff~20 minCommon in Networking & APIs interviewsIndustries Software development, Technology

Question

Review this Python webhook consumer that should process each event exactly once.

What a strong answer looks like

Separate real bugs from style. Rank issues by severity, point at the root cause rather than the symptom, and suggest a concrete fix — specific and kind.

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Talk through your review

Code to reviewpython

1def handle(event):2    if seen.exists(event.id):3        return4    send_fulfillment_email(event)   # external side effect5    charge_customer(event)          # external side effect6    seen.add(event.id)              # mark processed

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