polling function

async function poll(fn, validate, interval = 2500) {
  const resolver = async (resolve, reject) => {
    try { // catch any error thrown by the "fn" function
      const result = await fn(); // fn does not need to be asynchronous or return promise
      // call validator to see if the data is at the state to stop the polling
      const valid = validate(result);

      if (valid === true) {
        resolve(result);
      } else if (valid === false) {
        setTimeout(resolver, interval, resolve, reject);
      } // if validator returns anything other than "true" or "false" it stops polling
    } catch (e) {
      reject(e);
    }
  };

  return new Promise(resolver);
}