code: def append_fields(self, new_fields):
          '''
          Add fields to the container
  
          :param new_fields: fields to append
          '''
          for field in new_fields:
              self.push(field)
              if isinstance(field, Container):
                  self.pop(f append_fields(self, new_fields):
          '''
          Add fields to the container
  
          :param new_fields: fields to append
          '''
          for field in new_fields:
              self.push(field)
              if isinstance(field, Container):
                  self.pop()
docs: Add fields to the container
  
          :param new_fields: fields to append