code: def build_field(self, field_name, info, model_class, nested_depth):
          
          if field_name in info.fields_and_pk:
              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)
  
          elif hasattr(model_class, field_name):
              return self.build_property_field(field_name, model_class)
  
          elif field_name == self.url_field_name:
              return self.build_url_field(field_name, model_class)
  
          return self.build_unknown_field(field_name, model_class)
docs: Return a two tuple of (cls, kwargs) to build a serializer field with.