      def save(self, **kwargs):
          """
          Save and return a list of object instances.
          """
          assert self.instance is None, (
              "Serializers do not support multiple update by default, only "
              "multiple create. For updates it is unclear how to deal with "
              "insertions and deletions. If you need to support multiple update, "
              "use a `ListSerializer` class and override `.save()` so you can "
              "specify the behavior exactly."
          )
  
          validated_data = [
              dict(list(attrs.items()) + list(kwargs.items()))
              for attrs in self.validated_data
          ]
  
 
</s> remove         self.instance = [
            self.child.create(attrs) for attrs in validated_data
        ]
 </s> add         if self.instance is not None:
            self.instance = self.update(self.instance, validated_data)
            assert self.instance is not None, (
                '`update()` did not return an object instance.'
            )
        else:
            self.instance = self.create(validated_data)
            assert self.instance is not None, (
                '`create()` did not return an object instance.'
            )
      def save(self, **kwargs):
          """
          Save and return a list of object instances.
          """








          validated_data = [
              dict(list(attrs.items()) + list(kwargs.items()))
              for attrs in self.validated_data
          ]
  
keep keep keep keep replace replace replace replace replace replace replace replace keep keep keep keep keep
 Split out .create and .update on ListSerializer 
rest_framework/serializers.py