add tests for output, plus other nits

[depial]

• Added the tests for the output of the function title.
• Included @colinleach as an author
• Refined exemplar.jl to incorporate all parts of the final exercise

[github-actions]

This PR touches files which potentially affect the outcome of the tests of an exercise. This will cause all students' solutions to affected exercises to be re-tested.

If this PR does not affect the result of the test (or, for example, adds an edge case that is not worth rerunning all tests for), please add the following to the merge-commit message which will stops student's tests from re-running. Please copy-paste to avoid typos.

[no important files changed]

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