code: func RegisterDefaultProtocols(r *Registry) {
  	registerPlatformProtocols(r)
  
  	// Register common protocols.
  	r.Register("tcp4", tcpProtocolClientFactory("tcp4"))
  	r.Register("tcp6", tcpProtocolClientFactory("tcp6"))
  }
docs: // RegisterDefaultProtocols registers the default set of protocols with a
  // Registry.