function isValidStatusCode (code) {
  if (code >= 1000 && code < 1015) {
    return (
      code !== 1004 && // reserved
      code !== 1005 && // "MUST NOT be set as a status code"
      code !== 1006 // "MUST NOT be set as a status code"
    )
  }

  return code >= 3000 && code <= 4999
}
@see https://datatracker.ietf.org/doc/html/rfc6455#section-7-4
@param {number} code
@returns {boolean}