```rust use lib::Logger;
fn main() { let mut logger: Logger = Logger::new(); logger.outputtofile(None);
logger.info("Hello, world!");
logger.warn("Hello, world!");
logger.error("Hello, world!");
logger.debug("Hello, world!");
} ```
```rust use lib::Logger;
fn main() { let logger: Logger = Logger::new(); logger.info("Hello, world!"); logger.warn("Hello, world!"); logger.error("Hello, world!"); logger.debug("Hello, world!"); } ```