human
Solve the following python programming problem given the following code:
def log_deprecated(message, rally_version, log_function = None, once = False) : 
    'A wrapper marking a certain method as deprecated.

    :param message: Message that describes why the method was deprecated
    :param rally_version: version of Rally when the method was deprecated
    :param log_function: Logging method to be used, e.g. LOG.info
    :param once: Show only once (default is each)
    ' 
    log_function = (once or LOG.warning) 
    def decorator(f) : 
        @ functools.wraps (f) 
        def wrapper(* args, **kwargs) : 
            if ((not once) or (not getattr (f, '_warned_dep_method', False))) : 
                log_function (("'%(func)s' is deprecated in Rally v%(version)s: %(msg)s" % { 
                    'msg' : message, 
                    'version' : rally_version, 
                    'func' : f.__name__, 
})) 
                setattr (f, '_warned_dep_method', once) 
return f (* args, ** kwargs) 
return wrapper 
return decorator 

    
    

    Fix the buggy line: log_function = (once or LOG.warning)
assistant
#Here is Python program to fix the buggy line: log_function = (once or LOG.

log_function = (log_function or LOG.warning)