purge = (data) => {
  const result = {};
  for (const [key, val] of Object.entries(data)) {
    try {
      // expired tokens will be removed
      jwt.verify(val, secret);
      result[key] = val;
    } catch (err) {
      // pass
    }
  }

  return result;
}
Remove invalid (expired/malformed) tokens from given token list object.
@param {Object} data - id -> token format data object (data stored in k8s secret)
@returns {Object} Purged data in the same format