Function init 

pub fn init(
    log_level: &str,
    log_format: &LogFormat,
    log_with_ansi: bool,
    log_file: Option<&Path>,
) -> Result

Logging system initialization.

Sets up a global tracing subscriber that streams events to stderr and, optionally, to a file. Returns an error if the global subscriber was already initialized or if the log file cannot be opened.