public static function loadFunctionMap()
    {
        $fm = new self();

        $fm->addFunction('keyMatch', function (...$args) {
            return BuiltinOperations::keyMatchFunc(...$args);
        });
        $fm->addFunction('keyMatch2', function (...$args) {
            return BuiltinOperations::keyMatch2Func(...$args);
        });
        $fm->addFunction('regexMatch', function (...$args) {
            return BuiltinOperations::regexMatchFunc(...$args);
        });
        $fm->addFunction('ipMatch', function (...$args) {
            return BuiltinOperations::iPMatchFunc(...$args);
        });

        return $fm;
    }