title: How to call serializer's create() method from one serializer
body: <p>I have two serializers, "UserSerializer" and "CustomerSerializer" as bellow</p>
  
  <pre><code>class UserSerializer(serializers.ModelSerializer):
  
      def create(self, validated_data):
          return User.objects.create(**validated_data)
  
      class Meta:
          model = User
          fields = '__all__'
  
  
  class CustomerSerializer(serializers.ModelSerializer):
  
      def create(self, validated_data):
          return Customer.objects.create(**validated_data)
  
      class Meta:
          model = Customer
          fields = '__all__'
  </code></pre>
  
  <p>When I hit user api with POST request, it calls UserSerializer's create method which saves user object.</p>
  
  <p>Now while saving user I want to save customer object as well, using user api. So for from UserSerializer's create method I want to call CustomerSerializer's create() method in order to save customer object as well. How do I do that ?</p>