mux.go
func (mx *Mux) Delete(pattern string, handlerFn http.HandlerFunc) {
	mx.handle(mDELETE, pattern, handlerFn)
}
func (mx *Mux) Delete(pattern string, handlerFn http.HandlerFunc) {
	mx.handle(mDELETE, pattern, handlerFn)
}
// Delete adds the route `pattern` that matches a DELETE http method to
// execute the `handlerFn` http.HandlerFunc.