def comment_doc(doc, comment_text):
return annotate(CommentAnnotation(comment_text), doc)<EOL>
Annotates a Doc with a comment; used by the layout algorithm.

    You don't need to call this unless you're doing something low-level
    with Docs; use ``comment`` instead.

    ``prettyprinter`` will make sure the parent (or top-level) handler
    will render the comment in a proper way. E.g. if ``doc``
    represents an element in a list, then the ``list`` pretty
    printer will handle where to place the comment.