def __set_identifier(self, value):
        '''
        Sets the ID of the invoice.
        @param value:str
        '''
        if not value or not len(value):
            raise ValueError("Invalid invoice ID")

        self.__identifier = value
def __set_identifier ( self , value ) : if not value or not len ( value ) : raise ValueError ( "Invalid invoice ID" ) self . __identifier = value
Sets the ID of the invoice.
        @param value:str