old_contents: from datetime import datetime
  
  from tools import singleton
  
  
  @singleton
  class Logger(object):
      def d(self, tag, message):
          print self.format("DEBUG", tag, message)
  
      def e(self, tag, message):
          print self.format("ERROR", tag, message)
  
      def i(self, tag, message):
          print self.format("INFO", tag, message)
  
      def format(self, level, tag, message):
          return level + " " + datetime.now().strftime('%Y-%m-%d %H:%M:%S') + " " + tag + message
  
new_contents: from datetime import datetime
  
  from tools import singleton
  
  
  @singleton
  class Logger(object):
      def d(self, tag, message):
          print self.format("DEBUG", tag, message)
  
      def e(self, tag, message):
          print self.format("ERROR", tag, message)
  
      def i(self, tag, message):
          print self.format("INFO", tag, message)
  
      def format(self, level, tag, message):
          return level + " " + datetime.now().strftime('%Y-%m-%d %H:%M:%S') + " " + tag + " " + message
  
subject: Fix logger