              ret[info.pk.name] = serializer_pk_field
  
          # Regular fields
          for field_name, field in info.fields.items():
              ret[field_name] = self.get_field(field)
  
          # Forward relations
          for field_name, relation_info in info.forward_relations.items():
              if self.opts.depth:
                  ret[field_name] = self.get_nested_field(*relation_info)
 
</s> remove             ret[info.pk.name] = serializer_pk_field
 </s> add             ret[field_name] = serializer_pk_field </s> remove                 ret[field_name] = self.get_nested_field(*relation_info)
 </s> add                 ret[field_name] = self.get_nested_field(field_name, *relation_info) </s> remove                 ret[field_name] = self.get_related_field(*relation_info)
 </s> add                 ret[field_name] = self.get_related_field(field_name, *relation_info) </s> remove         serializer_pk_field = self.get_pk_field(info.pk)
 </s> add         field_name = info.pk.name
        serializer_pk_field = self.get_pk_field(field_name, info.pk) </s> remove                     ret[accessor_name] = self.get_nested_field(*relation_info)
 </s> add                     ret[accessor_name] = self.get_nested_field(accessor_name, *relation_info)
            ret[field_name] = self.get_field(field_name, field)
              ret[info.pk.name] = serializer_pk_field
  
          # Regular fields
          for field_name, field in info.fields.items():
            ret[field_name] = self.get_field(field_name, field)
  
          # Forward relations
          for field_name, relation_info in info.forward_relations.items():
              if self.opts.depth:
                  ret[field_name] = self.get_nested_field(*relation_info)
keep keep keep keep replace keep keep keep keep keep
 Drop label from serializer fields when not needed 
rest_framework/serializers.py