function validate(x: number): Promise<number> {
  return x > 0 ? Promise.resolve(x) : Promise.reject(new Error("inválido"));
}
function transform(x: number): Promise<number> {
  return Promise.resolve(x * 10);
}

function safeProcess(x: number): Promise<number> {
  return validate(x).then(transform).catch(() => -1)
}

export { safeProcess };