Function setup_logging 

pub fn setup_logging(
    config: &LoggingConfig,
    mistrust: &Mistrust,
    path_resolver: &CfgPathResolver,
    cli: Option<&str>,
) -> Result<LogGuards>

Set up logging.

Note that the returned LogGuard must be dropped precisely when the program quits; they’re used to ensure that all the log messages are flushed.