IOClient([innerClient ])

Creates a new HTTP client.

innerClient must be a dart:io HTTP client. If it's not passed, a default one will be instantiated.

Source 

IOClient([dynamic innerClient]) {
  io.assertSupported("IOClient");
  if (innerClient != null) {
    // TODO(nweiz): remove this assert when we can type [innerClient]
    // properly.
    assert(io.isHttpClient(innerClient));
    _inner = innerClient;
  } else {
    _inner = io.newHttpClient();
  }
}