          if parent.opts.depth:
              self.opts.depth = parent.opts.depth - 1
  
      #####
      # Methods to convert or revert from objects <--> primitive representations.
  
      def get_field_key(self, field_name):
          """
 
</s> remove     def __init__(self, instance=None, data=None, files=None, context=None, partial=False, **kwargs):
 </s> add     def __init__(self, instance=None, data=None, files=None,
                 context=None, partial=False, **kwargs): </s> remove     ManyToManyModel, Person, ReadOnlyManyToManyModel)
 </s> add     ManyToManyModel, Person, ReadOnlyManyToManyModel, Photo) </s> remove             # Set up the field
            field.initialize(parent=self, field_name=key)
 </s> add 
        # We need to call initialize here to ensure any nested
        # serializers that will have already called initialize on their
        # descendants get updated with *their* parent.
        # We could be a bit more smart about this, but it'll do for now.
        for key, field in self.fields.items():
            field.initialize(parent=self, field_name=key)

          if parent.opts.depth:
              self.opts.depth = parent.opts.depth - 1
  
        # We need to call initialize here to ensure any nested
        # serializers that will have already called initialize on their
        # descendants get updated with *their* parent.
        # We could be a bit more smart about this, but it'll do for now.
        for key, field in self.fields.items():
            field.initialize(parent=self, field_name=key)

      #####
      # Methods to convert or revert from objects <--> primitive representations.
  
      def get_field_key(self, field_name):
          """
keep keep add keep keep keep keep keep
 Clean up field initialization.  Fixes #497 
rest_framework/serializers.py