middleware helmet changes.

router check and panic message change.
README enhancement

router.go

@@ -30,55 +30,65 @@ func (r *Router) Use(h ...func(http.Handler) http.Handler) {
 
 // GET method route
 func (r *Router) GET(pattern string, h http.HandlerFunc) {
-	r.handlerFunc(http.MethodGet, pattern, h)
+	r.handle(http.MethodGet, pattern, h)
 }
 
 // HEAD method route
 func (r *Router) HEAD(pattern string, h http.HandlerFunc) {
-	r.handlerFunc(http.MethodHead, pattern, h)
+	r.handle(http.MethodHead, pattern, h)
 }
 
 // POST method route
 func (r *Router) POST(pattern string, h http.HandlerFunc) {
-	r.handlerFunc(http.MethodPost, pattern, h)
+	r.handle(http.MethodPost, pattern, h)
 }
 
 // PUT method route
 func (r *Router) PUT(pattern string, h http.HandlerFunc) {
-	r.handlerFunc(http.MethodPut, pattern, h)
+	r.handle(http.MethodPut, pattern, h)
 }
 
 // PATCH method route
 func (r *Router) PATCH(pattern string, h http.HandlerFunc) {
-	r.handlerFunc(http.MethodPatch, pattern, h)
+	r.handle(http.MethodPatch, pattern, h)
 }
 
 // DELETE method route
 func (r *Router) DELETE(pattern string, h http.HandlerFunc) {
-	r.handlerFunc(http.MethodDelete, pattern, h)
+	r.handle(http.MethodDelete, pattern, h)
 }
 
 // CONNECT method route
 func (r *Router) CONNECT(pattern string, h http.HandlerFunc) {
-	r.handlerFunc(http.MethodConnect, pattern, h)
-} // OPTIONS method route
+	r.handle(http.MethodConnect, pattern, h)
+}
+
+// OPTIONS method route
 func (r *Router) OPTIONS(pattern string, h http.HandlerFunc) {
-	r.handlerFunc(http.MethodOptions, pattern, h)
+	r.handle(http.MethodOptions, pattern, h)
 }
 
 // TRACE method route
 func (r *Router) TRACE(pattern string, h http.HandlerFunc) {
-	r.handlerFunc(http.MethodTrace, pattern, h)
+	r.handle(http.MethodTrace, pattern, h)
 }
 
-// HandleFunc registers the handler function for the given pattern.
+// handle registers the handler for the given pattern.
 // If the given pattern conflicts, with one that is already registered, HandleFunc
 // panics.
-func (r *Router) handlerFunc(method, pattern string, h http.HandlerFunc) {
+func (r *Router) handle(method, pattern string, h http.HandlerFunc) {
 	if r == nil {
 		panic("mux: func Handle() was called on nil")
 	}
 
+	if strings.TrimSpace(pattern) == "" {
+		panic("mux: pattern cannot be empty")
+	}
+
+	if !strings.HasPrefix(pattern, "/") {
+		pattern = "/" + pattern
+	}
+
 	path := fmt.Sprintf("%s %s", method, pattern)
 	r.mux.Handle(path, stack(r.middlewares, h))
 }
@@ -101,7 +111,7 @@ func (r *Router) With(middleware ...func(http.Handler) http.Handler) *Router {
 // path, with a fresh middleware stack for the inline-Router.
 func (r *Router) Group(fn func(grp *Router)) {
 	if r == nil {
-		panic("mux: Resource() called on nil")
+		panic("mux: Group() called on nil")
 	}
 
 	if fn == nil {
@@ -143,7 +153,7 @@ func (r *Router) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 	r.mux.ServeHTTP(w, req)
 }
 
-// TODO: proxy for aws lambda
+// TODO: proxy for aws lambda and other serverless platforms
 
 // stack middlewares(http handler) in order they are passed (FIFO)
 func stack(middlewares []func(http.Handler) http.Handler, endpoint http.Handler) http.Handler {