Code Readability Basics: Guided Lab

Time: 90 minutes. Implement a measurement summary with count and optional mean. Specify empty, negative, and invalid inputs. Write behavior tests before extracting one helper.

Acceptance: empty and zero-valued datasets remain distinguishable, the refactor preserves behavior, and a reader can explain the contract from the interface. Include a review note describing an extraction you rejected and why.

Review and remediation

Submit the starting failure, intermediate trace, final result, and one limitation. Explain the result without running the implementation. If the acceptance check fails, return to the matching worked example, correct the model, then use a fresh input before resubmitting. Record any AI assistance and which claims you independently checked.