def logging_arguments(parser, core=core):
    """Logging command line arguments, allows override of the core class
    instance where required.

    `parser`
        Instance of ArgumentParser.
    `core`
        Package core instance.
    """
    log_level_kwargs = {'type': str, 'default': core.DEFAULT_LOG_LEVEL,
        'metavar': 'LEVEL', 'help': 'logging level'}
    parser.add_argument('-l', **log_level_kwargs)
    log_file_kwargs = {'type': str, 'default': core.DEFAULT_LOG_FILE,
        'metavar': 'FILE', 'help': 'logging file'}
    parser.add_argument('--log-file', **log_file_kwargs)
