I have a selection field and this function for list items in field by dynamically.

def get_years(self):
        year_list = []
        year = date.today().year+1
        lastyear = date.today().year - 20
        for i in range(int(lastyear),int(year)):
            year_list.append((i, str(i)))
        return year_list

this is the field,

year = fields.Selection(get_years, string='Yıl', default=get_current_year, restore="True")

and when i save the form, this field become unknown. I found what is the problem but dont know the solution. Problem is compute function, when i write items like [(1997,1997),(2016,2016),(2017,2017)] it is working but i dont want to write hard code. How can i solve this problem. Thank you.