Declare option not options

client/client.go

@@ -16,12 +16,18 @@ type options struct {
 	transport transport.Transport
 }
 
-type Options func(*options)
+type Option func(*options)
 
 var (
 	DefaultClient Client = NewRpcClient()
 )
 
+func Transport(t transport.Transport) Option {
+	return func(o *options) {
+		o.transport = t
+	}
+}
+
 func Call(request Request, response interface{}) error {
 	return DefaultClient.Call(request, response)
 }