old_contents: # Copyright (C) 2013 Yahoo! Inc. All Rights Reserved.
  #
  # Licensed under the Apache License, Version 2.0 (the "License"); you may
  # not use this file except in compliance with the License. You may obtain
  # a copy of the License at
  #
  # http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  # License for the specific language governing permissions and limitations
  # under the License.
  
  import abc
  
  import six
  
  
  @six.add_metaclass(abc.ABCMeta)
  class Backend(object):
      """Base class for persistence backends."""
  
      def __init__(self, conf):
          if not conf:
              conf = {}
          if not isinstance(conf, dict):
              raise TypeError("Configuration dictionary expected not: %s"
                              % type(conf))
          self._conf = conf
          self._audit = 'audit'
          self._repair = 'repair'
  
      @abc.abstractmethod
      def open(self):
          pass
  
      @abc.abstractmethod
      def close(self):
          """Closes any resources this backend has open."""
          pass
  
new_contents: # Copyright (C) 2013 Yahoo! Inc. All Rights Reserved.
  #
  # Licensed under the Apache License, Version 2.0 (the "License"); you may
  # not use this file except in compliance with the License. You may obtain
  # a copy of the License at
  #
  # http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  # License for the specific language governing permissions and limitations
  # under the License.
  
  import abc
  
  import six
  
  
  @six.add_metaclass(abc.ABCMeta)
  class Backend(object):
      """Base class for persistence backends."""
  
      def __init__(self, conf):
          if not conf:
              conf = {}
          if not isinstance(conf, dict):
              raise TypeError("Configuration dictionary expected not: %s"
                              % type(conf))
          self._conf = conf
          self._audit = 'audit'
          self._repair = 'repair'
  
      @abc.abstractmethod
      def open(self):
          pass
  
      @abc.abstractmethod
      def close(self):
          """Closes any resources this backend has open."""
          pass
  
      @abc.abstractmethod
      def get_audits(self):
          pass
  
      @abc.abstractmethod
      def get_repairs(self):
          pass
  
      @abc.abstractmethod
      def audit_cfg_from_name(self, name):
          pass
  
      @abc.abstractmethod
      def repair_cfg_from_name(self, name):
          pass
  
      @abc.abstractmethod
      def get_script_cfg(self, script_type):
          pass
  
      @abc.abstractmethod
      def check_script_exists(self, script_type, script_name):
          pass
  
      @abc.abstractmethod
      def add_script(self, script_type, data):
          pass
  
subject: Add some abstract methods to backend