code: def update_default(self, new_default, respect_none=False):
          
          if new_default is not None:
              self.default = new_default
          elif new_default is None and respect_none:
              self.default = None
docs: Update our current default with the new_default.
  
          Args:
              new_default: New default to set.
              respect_none: Flag to determine if ``None`` is a valid value.