Is there an error in the documentation page: https://coderunner.org.nz/mod/book/view.php?id=198&chapterid=803
It states: The prototype also defines whether the correctness of the student's submission is assessed by use of an EqualityGrader, a NearEqualityGrader or RegexGrader.
But isn't there another type of grader, not mentioned, where the question author can examine the student text programmatically and print a json string which tells the system what the student grade and feedback are?