*
   *  * A regular host name, like `android.com`.
   *
   *  * An IPv4 address, like `127.0.0.1`.
   *
   *  * An IPv6 address, like `::1`. Note that there are no square braces.
   *
   *  * An encoded IDN, like `xn--n3h.net`.
   *
   * | URL                   | `host()`        |
   * | :-------------------- | :-------------- |
   * | `http://android.com/` | `"android.com"` |