import logging


def logged(class_):
    """Class-level decorator to insert logging.
    
    This assures that a class has a ``.log`` member.
    
    ::
    
        @logged
        class Something:
            def __init__(self, args):
                self.log(f"init with {args}")
    """
    class_.log= logging.getLogger(class_.__qualname__)
    return class_