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Grade 8 · unit review

Review: Work with Collections and Defensive Inputs

Given counts={"A":4,"B":7}, retrieve B and test whether 7 appears in[4,7]. Design a 0–10 integer input rule and explain why an alias is not an independent backup.

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Unit review questions
1. Paper Python 3 expression: "green" in ["red","blue"]. What value results?
Need a hint?
  • Check whether the queried value exists anywhere in the supplied collection.
  • A true membership result is not a numeric occurrence count.
2. Paper Python 3 expression: {"small":2,"large":10}["large"]. What value results?
Need a hint?
  • Look up the exact supplied key and report its associated value.
  • Do not retrieve a dictionary value by guessing list-like row order.
3. Integer-1. Contract: count must be an integer 0–10; Boolean is not accepted. Classify the input.
Need a hint?
  • Check type and range before accepting a count into the stated workflow.
  • Converting or clipping an invalid input silently may change its meaning.
4. Source list itself is sorted in place. Classify the stated result.
Need a hint?
  • Compare the source before/after record and distinguish a new result from a mutation.
  • Assigning another name to the same mutable object is not automatically an independent copy.

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Given counts={"A":4,"B":7}, retrieve B and test whether 7 appears in[4,7]. Design a 0–10 integer input rule and explain why an alias is not an independent backup.

Work on paper or in your own document. Explain the choices you made.

  • Use only supplied fictional inputs and state the relevant rule.
  • Include labeled steps or evidence for each decision.
  • Name one limitation or tempting mistake.
  • Check that the result meets the task and revise a justified error.
Compare with a model response

counts["B"] is 7 and 7 in[4,7] isTrue. Validate integer type, exclude Booleans and enforce 0–10 before updating. A second name referring to the same list shares mutations, so it is not an independent recovery copy.

A different response can also meet the criteria. Compare the evidence and reasoning, rather than copying the wording.