docs: def widget_attrs(self, widget):
          """
          Given a Widget instance (*not* a Widget class), returns a dictionary of
          any HTML attributes that should be added to the Widget, based on this
          Field.
          """
          attrs = {}
          if getattr(self, "min_value", None) is not None:
              attrs['min'] = self.min_value
          if getattr(self, "max_value", None) is not None:
              attrs['max'] = self.max_value
          return attrs