old_contents: import msgpack
  import logging
  
  from elevator.constants import FAILURE_STATUS
  
  
  class MessageFormatError(Exception):
      pass
  
  
  class Request(object):
      """Handler objects for frontend->backend objects messages"""
      def __new__(cls, *args, **kwargs):
          content = {
              'DB_UID': kwargs.pop('db_uid'),
              'COMMAND': kwargs.pop('command'),
              'ARGS': kwargs.pop('args'),
          }
  
          return msgpack.packb(content)
  
  
  class Response(object):
      def __init__(self, raw_message):
          self.error = None
          errors_logger = logging.getLogger("errors_logger")
          message = msgpack.unpackb(raw_message)
  
          try:
              self.status = message.pop('STATUS')
              self._datas = message.pop('DATAS')
          except KeyError:
              errors_logger.exception("Invalid response message : %s" %
                                      message)
              raise MessageFormatError("Invalid response message")
  
          self._handle_failures()
  
      @property
      def datas(self):
          if hasattr(self, '_datas') and self._datas is not None:
              if (len(self._datas) == 1):
                  return self._datas[0]
              return self._datas
  
      def _handle_failures(self):
          if self.status == FAILURE_STATUS:
              self.error = {
                  'code': int(self.datas[0]),
                  'msg': self.datas[1],
              }
  
new_contents: import msgpack
  import logging
  
  from .constants import FAILURE_STATUS
  
  
  class MessageFormatError(Exception):
      pass
  
  
  class Request(object):
      """Handler objects for frontend->backend objects messages"""
      def __new__(cls, *args, **kwargs):
          content = {
              'DB_UID': kwargs.pop('db_uid'),
              'COMMAND': kwargs.pop('command'),
              'ARGS': kwargs.pop('args'),
          }
  
          return msgpack.packb(content)
  
  
  class Response(object):
      def __init__(self, raw_message):
          self.error = None
          errors_logger = logging.getLogger("errors_logger")
          message = msgpack.unpackb(raw_message)
  
          try:
              self.status = message.pop('STATUS')
              self._datas = message.pop('DATAS')
          except KeyError:
              errors_logger.exception("Invalid response message : %s" %
                                      message)
              raise MessageFormatError("Invalid response message")
  
          self._handle_failures()
  
      @property
      def datas(self):
          if hasattr(self, '_datas') and self._datas is not None:
              if (len(self._datas) == 1):
                  return self._datas[0]
              return self._datas
  
      def _handle_failures(self):
          if self.status == FAILURE_STATUS:
              self.error = {
                  'code': int(self.datas[0]),
                  'msg': self.datas[1],
              }
  
subject: Fix #6: Removed elevator constants useless import