old_contents: from rest_framework import serializers
  from .models import Relation, Variant
  
  
  class VariantSerializer(serializers.HyperlinkedModelSerializer):
      class Meta:
          model = Variant
          fields = ["tags"]
  
  
  class RelationSerializer(serializers.HyperlinkedModelSerializer):
      class Meta:
          model = Relation
          fields = ["tags"]
  
new_contents: from rest_framework import serializers
  from .models import Relation, Variant
  
  
  class VariantSerializer(serializers.HyperlinkedModelSerializer):
      """
      Serialize a Variant object.
      """
  
      b37_id = serializers.SerializerMethodField()
  
      class Meta:
          model = Variant
          fields = ['b37_id', 'tags']
  
      @staticmethod
      def get_b37_id(obj):
          """
          Return an ID like "1-883516-G-A".
          """
          return '-'.join([
              obj.tags['chrom_b37'],
              obj.tags['pos_b37'],
              obj.tags['ref_allele_b37'],
              obj.tags['var_allele_b37'],
          ])
  
  
  class RelationSerializer(serializers.HyperlinkedModelSerializer):
      """
      Serialize a Relation object.
      """
  
      class Meta:
          model = Relation
          fields = ['tags']
  
subject: Return the variant ID in the API