Logs a message at the specified log level.
The level at which to log the message.
The message to log.
Logs a debug-level message.
The message to log.
Logs an error-level message.
The message to log.
Logs an info-level message.
The message to log.
Logs a warning-level message.
The message to log.
Logs a message at the specified log level using a callback to generate the message.
The level at which to log the message.
A callback function that returns the message to log.
Sets the current log level. Messages at levels lower than this will be ignored.
The level to set for logging.
Interface for a logging system.