How to use the ref-napi.set function in ref-napi

const callback = _Callback(cif, retType.size, argc, errorReportCallback, (retval, params) => {
    debug('Callback function being invoked')
    try {
      const args = [];
      for (var i = 0; i < argc; i++) {
        const type = argTypes[i];
        const argPtr = params.readPointer(i * ref.sizeof.pointer, type.size);
        argPtr.type = type;
        args.push(argPtr.deref());
      }

      // Invoke the user-given function
      const result = func.apply(null, args);
      try {
        ref.set(retval, 0, result, retType);
      } catch (e) {
        e.message = 'error setting return value - ' + e.message;
        throw e;
      }
    } catch (e) {
      return e;
    }
  });