Describe the issue linked to the documentation

In the example exercises for working with text data, the text says to use CharNGramAnalyzer. Unless I am missing something, like that this is part of some other class, I cannot find this anywhere in the docs, nor in the code.
Documentation:
https://scikit-learn.org/stable/tutorial/text_analytics/working_with_text_data.html#exercise-1-language-identification

Suggest a potential alternative/fix

Based on what the answer is, whether this class does not exist anymore or refers to something else, I think the text exercise can be adapted. I can do a PR for this, once I know the answer. I also tried googling for an answer, so it might also be that I m missing something obvious that will explain it.