fix code formatting

en/02.7.md

@@ -61,7 +61,7 @@ goroutines run in the same memory address space, so you have to maintain synchro
 	cf := make(chan interface{})
 ```	
 channel uses the operator `<-` to send or receive data.
-```Go`
+```Go
 	ch <- v    // send v to channel ch.
 	v := <-ch  // receive data from ch, and assign to v
 ```