SubscribeMessage have been added

subscribe_message.go

@@ -0,0 +1,11 @@
+package overflow_subscriber
+
+type SubscribeMessage struct {
+	Targets []string             `json:"targets"`
+	Message SubscribeMessageBody `json:"message"`
+}
+
+type SubscribeMessageBody struct {
+	Method string      `json:"method"`
+	Params interface{} `json:"params,omitempty"`
+}