code: def restore_defaults(self):
          
          for key in self.default_values:
              self.restore_default(key)
  
          for section in self.sections:
              self[section].restore_defaults()
docs: Recursively restore default values to all members
          that have them.
  
          This method will only work for a ConfigObj that was created
          with a configspec and has been validated.
  
          It doesn't delete or modify entries without default values.