Write a log message (without newline). If the given verbosity level (lvl) is lower than it of the logger's, this will print out the given message. If the logger's verbosity level is L4, then this function will always print out messages regardless of the given `lvl`.

Write a log message with a newline. If the given verbosity level (lvl) is lower than it of the logger's, this will print out the given message. If the logger's verbosity level is L4, then this function will always print out messages regardless of the given `lvl`.