text: 
  # Copyright 2017-present Open Networking Foundation
  #
  # 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.
  
  
  class Invoker(object):
  
      def __init__(self, **args):
          pass
  
      # Method for handline pre save semantics
      #      content here would be model specific but could include handling Many-to-Many relationship
      #      creation - which must occur post save
      #
      # obj     - Whatever obj was just saved
      # returns - None - this is a pure invoke() call, return type is None
      #
      def presave(self, obj):
          return None
  
  
      # Method for handline post save semantics
      #      content here would be model specific but could include handling Many-to-Many relationship
      #      creation - which must occur post save
      #
      # obj     - Whatever obj was just saved
      # returns - None - this is a pure invoke() call, return type is None
      #
      def postsave(self, obj):
          return None