code: def discard_config(self):
          
          discard_candidate = 'copy running-config {}'.format(self._gen_full_path(self.candidate_cfg))
          discard_merge = 'copy null: {}'.format(self._gen_full_path(self.merge_cfg))
          self._disable_confirm()
          self.device.send_command_expect(discard_candidate)
          self.device.send_command_expect(discard_merge)
          self._enable_confirm()
docs: Set candidate_cfg to current running-config. Erase the merge_cfg file.