code: def underline(self, action):
          '''Enable/cancel underline printing
          
          Args:
              action -- Enable or disable underline printing. Options are '1' - '4' and 'cancel'
          Returns:
              None
          Raises:
              None
          '''
          if action == 'off':
              action = '0'
              self.send(chr(27)+chr(45)+action)
          else:
              self.send(chr(27)+chr(45)+actionf underline(self, action):
          '''Enable/cancel underline printing
          
          Args:
              action -- Enable or disable underline printing. Options are '1' - '4' and 'cancel'
          Returns:
              None
          Raises:
              None
          '''
          if action == 'off':
              action = '0'
              self.send(chr(27)+chr(45)+action)
          else:
              self.send(chr(27)+chr(45)+action)
docs: Enable/cancel underline printing
          
          Args:
              action -- Enable or disable underline printing. Options are '1' - '4' and 'cancel'
          Returns:
              None
          Raises:
              None