def comment_import(r, unused_dot_list):
    """Comment out import for {dot_str}."""
    unused_dot_str = ".".join(unused_dot_list)
    for n in r("ImportNode"):
        if n.names()[0] == unused_dot_str:
            # The "!" is inserted so that this line doesn't show up when searching for
            # the comment pattern in code.
            n.replace("#{}# {}".format("!", str(n)))
            break