class purchase_order_line ( models . Model )
    _inherit = "str"
    @ api . model
    def create ( self , vals ) :
        if "str" in vals and not "str" in vals
            vals [ "str" ] = self . env [ "str" ] . browse ( vals [ "str" ] ) . uom_po_id . id or 1
        res = super ( purchase_order_line , self ) . create ( vals )
        return res

class purchase_order_line ( models . Model ) :
    _inherit = "str"
    @ api . model
    def create ( self , vals ) :
        if "str" in vals and not "str" in vals :
            vals [ "str" ] = self . env [ "str" ] . browse ( vals [ "str" ] ) . uom_po_id . id or 1
        res = super ( purchase_order_line , self ) . create ( vals )
        return res

次に示すpythonコードの誤りを修正しなさい。