Log Levels

Log levels in the ascending order of severity

Log level	Usage in this library
trace	Internal trace logs for developer of this library.
debug	Log for debugging.
iteration	Log of each iteration.
iteration_label	Label of iteration logs. (Not usable for output log level.)
summary	Summary of calculations.
info	None. (Meant for use in user code to show some information.)
warning	Warnings of undesirable conditions.
error	Errors preventing further processing. (Usually used with exceptions.)
critical	None. (Meant for use in conditions which may cause death of processes.)
off	Turn off output. (Only for output log level.)