static function duplicateArgMessage($argName) { return "There can be only one argument named \"{$argName}\"."; }
private function duplicateArg($argName, $l1, $c1, $l2, $c2) { return FormattedError::create(UniqueArgumentNames::duplicateArgMessage($argName), [new SourceLocation($l1, $c1), new SourceLocation($l2, $c2)]); }