Keep 'spacebar' from being pressed twice

karabiner.json

                    {
                        "description": "Keep 'spacebar' from being pressed twice",
                        "manipulators":
                        [
                            {
                                "from": { "key_code": "spacebar" },
                                "parameters": { "basic.to_if_held_down_threshold_milliseconds": 50 },
                                "to_if_held_down":[
                                    {
                                        "key_code": "spacebar",
                                        "repeat": true
                                    }
                                ],
                                "type": "basic"
                            }
                        ]
                    }