PCEP Practice Question: Functions, Tuples, Dictionaries and Exceptions

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  shipment['destination'] or 'UNKNOWN'

  Why it's wrong here

  Indexing with a missing key raises KeyError immediately, and the `or` fallback is never reached because the exception interrupts evaluation. Even when the key exists, a legitimately empty string value would be replaced by 'UNKNOWN', which corrupts valid data. This does not give the safe, non-crashing behavior the logistics team requires for unreliable records.

• ✓

  shipment.get('destination', 'UNKNOWN')

  Why this is correct

  The dict.get method returns the value mapped to the key when the key exists, and it returns the second argument as a default when the key is absent, so missing keys never raise an error. In this scenario it yields 'Osaka' for the current record and 'UNKNOWN' for any record lacking a destination, letting the program continue processing shipments.

• ✗

  shipment.pop('destination', 'UNKNOWN')

  Why it's wrong here

  pop removes the key from the dictionary and returns its value, so a successful lookup would delete the destination from the shipment record entirely. The team wants to keep the data intact for later reporting. Using pop also makes repeated reads inconsistent, since the first call succeeds and subsequent calls return the default instead of the real value.

• ✗

  shipment.setdefault('destination', 'UNKNOWN')

  Why it's wrong here

  setdefault does return 'UNKNOWN' for a missing key, but it also permanently inserts the key 'destination' with that value into the dictionary. That mutates the shipment record, so a later lookup can no longer distinguish a genuinely missing destination from one that was never supplied. The task only asks for a safe read, not a modification of the stored data.

Go deeper

Related to this question