How to use the @aurelia/jit.LetElementSymbol function in @aurelia/jit

bindLetElement(parentManifest, node) {
        const symbol = new LetElementSymbol(this.dom, node);
        parentManifest.childNodes.push(symbol);
        const attributes = node.attributes;
        let i = 0;
        while (i < attributes.length) {
            const attr = attributes[i];
            if (attr.name === 'to-view-model') {
                node.removeAttribute('to-view-model');
                symbol.toViewModel = true;
                continue;
            }
            const attrSyntax = this.attrParser.parse(attr.name, attr.value);
            const command = this.resources.getBindingCommand(attrSyntax);
            const bindingType = command == null ? 2048 /* Interpolation */ : command.bindingType;
            const expr = this.exprParser.parse(attrSyntax.rawValue, bindingType);
            const to = camelCase(attrSyntax.target);
            const info = new BindableInfo(to, BindingMode.toView);

private bindLetElement(parentManifest: IElementSymbol, node: HTMLElement): void {
    const symbol = new LetElementSymbol(this.dom, node);
    parentManifest.childNodes.push(symbol);

    const attributes = node.attributes;
    let i = 0;
    while (i < attributes.length) {
      const attr = attributes[i];
      if (attr.name === 'to-view-model') {
        node.removeAttribute('to-view-model');
        symbol.toViewModel = true;
        continue;
      }
      const attrSyntax = this.attrParser.parse(attr.name, attr.value);
      const command = this.resources.getBindingCommand(attrSyntax, false);
      const bindingType = command == null ? BindingType.Interpolation : command.bindingType;
      const expr = this.exprParser.parse(attrSyntax.rawValue, bindingType);
      const to = camelCase(attrSyntax.target);