i have field Char

qr_code = fields.Char(string='QR CODE')
lot_qr = fields.Char(string='LOT', compute='calculate_qr_code_fun')

 ex : qr_code = '010628108600022910110553172108012100000000000H45'

i need too know also if i can assign the value by domain 

like if there is <10 > start till reach to< 17> for example 

lot_qr = '110553​'

i tried this : 

@api.model
def calculate_qr_code_fun(self, qr_code):
    self.lot_qr = qr_code.spilt('14', 1)[0]