Log
The severity of a log. From most to least severe:
When using Logback (on the JVM), you can enable/disable log levels for loggers based on their package names (see Logback configuration docs). You also set a "root" (default) log level - if this level is INFO, then DEBUG/TRACE logs will not produce any output unless explicitly enabled for a logger.
Log levels are implemented as static instances on the companion object, instead of as an enum. This is because we don't want to bind ourselves to the public API that an enum exposes (Enum.name and Enum.ordinal).