Question 79 of 498
PCEP Practice Question: Data Types, Variables, Basic I/O and Operators
Exhibit
Refer to the exhibit.
JSON policy:
{
"policy": "allow",
"ports": [80, 443]
}A Python script reads this JSON and needs to check if port 8080 is allowed. Which expression correctly checks? Assume data is already parsed into a dictionary.
⚠ Common exam trap
Python Institute often tests the distinction between checking for a key in a dictionary (`key in dict`) versus checking for a value in a list (`value in list`), and candidates mistakenly use `contains()` (from Java or other languages) or confuse dictionary key existence with list membership.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
8080 in data["ports"]
The `in` operator checks for membership in a list. Since `data["ports"]` is a list (e.g., `[80, 443, 8080]`), `8080 in data["ports"]` returns `True` if 8080 is present. This directly tests whether port 8080 is allowed.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
data["ports"].contains(8080)
Why it's wrong here
Lists do not have a .contains() method.
- ✗
data.get("ports") == 8080
Why it's wrong here
Compares list to integer, always False.
- ✓
8080 in data["ports"]
Why this is correct
Correct; checks if 8080 is in the list.
- ✗
"ports" in data
Why it's wrong here
Checks if key exists, not port value.
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Last reviewed: Jun 30, 2026
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