Let's look at a simple program that returns a set of words as an HTTP response based on bookID:

package main 
 
import ( 
    "log" 
    "net/http" 
) 
 
func reqHandler(w http.ResponseWriter, r *http.Request) { 
    books := map[string]string{ 
        "book1": 'apple apple cat zebra', 
        "book2": 'banana cake zebra', 
        "book3": 'apple cake cake whale', 
    } 
 
    bookID := r.URL.Path[1:] 
    book, _ := books[bookID] 
    w.Write([]byte(book)) 
} 
 
func main() { 
 
    log.Println("Starting File Server on Port :9876...") 
    http.HandleFunc("/", reqHandler) 
    http.ListenAndServe(":9876", nil) 
}