docs: def export_deleted_fields(self):
          """
          Resturns a list with any deleted fields form original data.
          In tree models, deleted fields on children will be appended.
          """
          result = self.__deleted_fields__.copy()
  
          for key, value in self.__original_data__.items():
              if key in result:
                  continue
              try:
                  partial = value.export_deleted_fields()
                  result.extend(['.'.join([key, key2]) for key2 in partial])
              except AttributeError:
                  pass
  
          return result