code: func Dial(network, addr string) (net.Conn, error) {
  	if usingProxy {
  		return dialWithFallback(proxyDialer.Dial, net.Dial, network, addr)
  	}
  	return net.Dial(network, addr)
  }
docs: // Dial tries dialing via proxy if a proxy is configured, and falls back to
  // a direct connection if no proxy is defined, or connecting via proxy fails.