Revert back to using http.Handler type for the router

This reverts commit 0afafd97fdb24a031dc12e39a5c860a669e694d0.

main.go

@@ -14,7 +14,9 @@ func contactHandler(w http.ResponseWriter, r *http.Request) {
 	fmt.Fprint(w, "<h1>Contact Page</h1><p>To get in touch, email me at <a href=\"mailto:example@example.com\">example@example.com</a></p>")
 }
 
-var pathHandler http.HandlerFunc = func(w http.ResponseWriter, r *http.Request) {
+type Router struct{}
+
+func (router Router) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	switch r.URL.Path {
 	case "/":
 		homeHandler(w, r)
@@ -29,6 +31,7 @@ var pathHandler http.HandlerFunc = func(w http.ResponseWriter, r *http.Request)
 }
 
 func main() {
+	var router Router
 	fmt.Println("Starting the server on :3000...")
-	http.ListenAndServe(":3000", pathHandler)
+	http.ListenAndServe(":3000", router)
 }