| function method | description |
|---|---|
| add | add a value to an existing key. If the key doesn’t exist, it will be defined and the value is added. |
| set | set overwrite the existing value with the new one. If the key doesn’t exist, it will be defined and the value is added. |
| clear | clear deletes / removes all value in an existing key. |
| remove | remove deletes the defined value in an existing key. |