Indeed, haven't read carefully, apologies.

Sometimes people might forget to capitalize the first letter of their name so your function should accommodate for these grammatical errors.

It's already there.

It would be nice to clarify in the presentation that some of the names start with a lowercase letter and are expected to be considered valid

Thank you for the feedback, I am un-publishing it and re-working on it.

There already are kata about sorting lists, and about grouping lists. If you really want links to originals, I can find 'em. ( I have a groupBy kata myself .. )

Duplicate.

Spare us the input validation. See Docs -> Authoring -> Guidelines -> Kata Authoring Guidelines -> Task and Requirements -> Keep kata focused on one task. "Do one thing, and do it well."

Possibly spare us the splitting the string as well, because the function name indicates you are interested in sorting and grouping arrays with generic elements. Strings as encodings are suspicious and overrated. Use appropriate datatypes!