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: 
Dictionaries aren't ordered.

Add `sort_keys=True` to the `json.dumps()` invocation to always sort object keys in the JSON output.
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})

```