asMultiaddress = (value) => {
  // ignore empty string, as it will produce '/'
  if (value != null && value !== '') {
    try {
      return multiaddr(value).toString()
    } catch (_) {}
  }
  return null
}
Attempts to turn cast given value into Multiaddr.
Return either string instance or `null`.
@param {any} value
@returns {string|null}