Logging severity.

Constants
DEBUG = 0
 

Low-level information, mostly for developers

INFO = 1
 

generic, useful information about system operation

WARN = 2
 

a warning

ERROR = 3
 

a handleable error condition

FATAL = 4
 

an unhandleable error that results in a program crash

UNKNOWN = 5
 

an unknown message that should always be logged