when the user select the "Aérrienne" option i just want to add new options to the type_transport select
```python
mode_transport = fields.Selection([ ('Routière\Maritime','Routière\Maritime'), ('Routière','Routière'),('Aérrienne','Aérrienne') ],string="Mode de Transport") type_transport = fields.Selection([('test1','test1')],string="responsible")
@api.onchange("mode_transport")
def _set_type_transport(self):
if self.mode_trasport == False :
pass
elif self.mode_transport == 'Aérrienne' :
self.type_transport = fields.Selection(add_selection=[("new option","new option")])
```
