options.go
func Network(network string) Option {
	return Option(func(c *config) {
		c.Conn.Network = network
	})
}
func Network(network string) Option {
	return Option(func(c *config) {
		c.Conn.Network = network
	})
}
// Network sets the network (udp, tcp, etc) used by the client. See the
// net.Dial documentation (https://golang.org/pkg/net/#Dial) for the available
// network options.
//
// By default, network is udp. This option is ignored in Client.Clone().