new_contents: from rest_framework import serializers
  
  from poster.models import Post
  
  
  class PostSerializer(serializers.ModelSerializer):  # serializers.HyperlinkedModelSerializer):
  
      written_by = serializers.CharField()
  
      class Meta:
          model = Post
          fields = ('content', 'written_by', 'published_at')
  
subject: Add Post serializer.