Lambda - using gateway 301 error

i had added follow sameple code, zip and upload to aws lambda
but its not work for me...
Any suggestion please?

[

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```package main

import (
"fmt"
"log"
"net/http"
"os"

"github.com/apex/gateway"
)

func main() {
http.HandleFunc("/", hello)
log.Fatal(gateway.ListenAndServe(":3000", nil))
}

func hello(w http.ResponseWriter, r *http.Request) {
// example retrieving values from the api gateway proxy request context.
requestContext, ok := gateway.RequestContext(r.Context())
if !ok || requestContext.Authorizer["sub"] == nil {
fmt.Fprint(w, "Hello World from Go")
return
}

userID := requestContext.Authorizer["sub"].(string)
fmt.Fprintf(w, "Hello %s from Go", userID)
}

```