Mark submission as correct or incorrectSource:
Helper method to communicate that the user's submission was correct or
incorrect. These functions were originally designed for developers to create
question_is_correct() methods for custom question types, but they can also
be called inside the functions created by
answer_fn() to dynamically
determine the result and message provided to the user.
Returns a list with class
learnr_mark_as to be returned from the
question_is_correct() method for the learnr question type.