code: def init_widget(self):
          
          w = self.widget
          # Selection listener
          w.setAdapter(self.adapter)
          w.setOnItemSelectedListener(w.getId())
          w.onItemSelected.connect(self.on_item_selected)
          w.onNothingSelected.connect(self.on_nothing_selected)
          super(AndroidSpinner, self).init_widget()
docs: Initialize the underlying widget.