              model_field = info.fields_and_pk[field_name]
              return self.build_standard_field(field_name, model_field)
  
          elif field_name in info.relations:
              if not nested_depth:
                  return self.build_relational_field(field_name, relation_info)
              else:
                  return self.build_nested_field(field_name, relation_info, nested_depth)
  
 
</s> remove                 return self.build_relational_field(field_name, info, model)
 </s> add                 return self.build_relational_field(field_name, relation_info) </s> remove                 return self.build_nested_field(field_name, info, model, nested_depth)
 </s> add                 return self.build_nested_field(field_name, relation_info, nested_depth) </s> remove             return self.build_standard_field(field_name, info, model)
 </s> add             model_field = info.fields_and_pk[field_name]
            return self.build_standard_field(field_name, model_field) </s> remove         if not issubclass(field_cls, HyperlinkedRelatedField):
            kwargs.pop('view_name', None)
 </s> add         if not issubclass(field_class, HyperlinkedRelatedField):
            field_kwargs.pop('view_name', None) </s> remove     def build_nested_field(self, field_name, info, model, nested_depth):
 </s> add     def build_nested_field(self, field_name, relation_info, nested_depth):
            relation_info = info.relations[field_name]
              model_field = info.fields_and_pk[field_name]
              return self.build_standard_field(field_name, model_field)
  
          elif field_name in info.relations:
            relation_info = info.relations[field_name]
              if not nested_depth:
                  return self.build_relational_field(field_name, relation_info)
              else:
                  return self.build_nested_field(field_name, relation_info, nested_depth)
  
keep keep keep add keep keep keep keep keep
 Final bits of docs for ModelSerializer fields API 
rest_framework/serializers.py