def init_formatter
      @formatter = proc do |s, d, p, m|
        "#{@format}\n" % { severity: s, datetime: d, progname: p, msg: m }
      end
    end
def init_formatter
      @formatter = proc do |s, d, p, m|
        "#{@format}\n" % { severity: s, datetime: d, progname: p, msg: m }
      end
    end
Initializes the logger's formatter proc based on the value of format
 instance variable. This method should only be called inside the register
 method
 @private