(self)
Only one of either a line item or invoice may be specified as the adjuster.
Only one of either a line item or invoice may be specified as the adjuster.
Only one of either a line item or invoice may be specified as the adjuster .
def clean(self):
        """
        Only one of either a line item or invoice may be specified as the adjuster.
        """
        if self.line_item and self.invoice:
            raise ValidationError(_("You can't specify both an invoice and a line item."))
def clean ( self ) : if self . line_item and self . invoice : raise ValidationError ( _ ( "You can't specify both an invoice and a line item." ) )