code: def update(self, instance, validated_data):
          
          instance.title = validated_data.get('title', instance.title)
          instance.code = validated_data.get('code', instance.code)
          instance.linenos = validated_data.get('linenos', instance.linenos)
          instance.language = validated_data.get('language', instance.language)
          instance.style = validated_data.get('style', instance.style)
          instance.save()
          return instance
docs: Update and return an existing `Snippet` instance, given the validated data.