def make_comment(content: str) ->str:
    """Return a consistently formatted comment from the given `content` string.

    All comments (except for "##", "#!", "#:", '#'", "#%%") should have a single
    space between the hash sign and the content.

    If `content` didn't start with a hash sign, one is provided.
    """
    content = content.rstrip()
    if not content:
        return '#'
    if content[0] == '#':
        content = content[1:]
    if content and content[0] not in " !:#'%":
        content = ' ' + content
    return '#' + content
