code: def _refresh_show(self, dt):
          
          d = self.declaration
          if dt <= 0:
              #: Done, hide
              d.show = False
          elif d.show:
              #: If user didn't cancel it, keep it alive
              self.toast.show()
  
              t = min(1000, dt)
              app = self.get_context()
              app.timed_call(t, self._refresh_show, dt-t)
docs: While the toast.show is true, keep calling .show() until the 
          duration `dt` expires.
  
          Parameters
          ------------
          dt: int
              Time left to keep showing