def <<(string = nil)
      message = ""
      message << delimiter
      message << string if string
      message << "\n" unless message[-1] == ?\n
      @buffer << message
      flush if @auto_flush

      message
    end
def <<(string = nil)
      message = ""
      message << delimiter
      message << string if string
      message << "\n" unless message[-1] == ?\n
      @buffer << message
      flush if @auto_flush

      message
    end
Appends a message to the log. The methods yield to an optional block and
 the output of this block will be appended to the message.

 ==== Parameters
 string<String>:: The message to be logged. Defaults to nil.

 ==== Returns
 String:: The resulting message added to the log file.