Challenge 2 — Solution

Task: A user sends the prompt "python: dictionaries exercises only."
Explain what this should produce, and why the wording of the modifier
matters based on PL2.

What this should produce: ONLY the exercise chapter for the
"dictionaries" topic in Python - a separate file containing at least
10 real, substantial challenges, each linked to its own worked .txt
solution, following PL3's own format. It should NOT produce the
standard topical lesson itself.

Why the wording matters: PL2 establishes that a plain PL1 request
(just "python: dictionaries," with no modifier at all) generates BOTH
the standard lesson AND its companion exercise chapter by default -
two files from one prompt. The "exercises only" phrase is what flips
that default specifically to produce just the exercise chapter alone,
skipping the main lesson entirely. This modifier is the correct choice
for exactly the situation PL2 itself names as its intended use case: a
lesson on "dictionaries" that may already exist from an earlier
request, now just needing its own exercise companion added afterward,
without regenerating (and potentially duplicating or overwriting) the
lesson that's already there.

Notes:
- The companion modifier, "no exercises" / "no ex", does the reverse -
  producing only the standard lesson and skipping the exercise chapter
  entirely - useful when exercises genuinely aren't wanted for a given
  topic.
- PL2 also notes matching is on the trailing phrase's own meaning, not
  exact punctuation - "python: dictionaries (exercises only)" or
  similar minor phrasing variations should still be recognized as the
  same request, with a genuinely ambiguous case meriting a clarifying
  question rather than a guess.