Question: The following is my settings by `crontab -e`, but it doesn't work.

```
*/20 * * * * export DISPLAY=:0.0;/usr/bin/notify-send "Take A Rest Please!" "Pay attention to your Eyes and Neck!" 

```

Answer: 
Python dict was `unordered` before Python 3.7. You could use `sort_keys=True` flag from `json.dumps()`. More about [json encoder and decoder](https://docs.python.org/2/library/json.html)
Because json in python is parsed as dictionary and normal dictionary in python is unordered if you want to be ordered you have use ordered dict

```
from collections import OrderedDict

OrderedDict({"a":1})

```