传递给appengine / file.Delete（）的fileName的值是？

I want to know is fileName to pass when you delete a file of gcs from gae/go.

Although passed "/gs/{bucketname}/{filename}", error message "RPC error UNKNOWN_ERROR:" is returned

package main

import (
    "appengine"
    "appengine/file"

    "net/http"
)

func handle(w http.ResponseWriter, r *http.Request) {
    c := appengine.NewContext(r)

    file.Delete(c, "/gs/{bucketname}/{filename}")
}

I'm not an expert on Go but to work with Cloud Storage you need the Google Cloud Storage Go Client Library as indicated here [1].

Take a look at this sample code [2], more specifically to the deleteFiles() fuction. You can see that the function to the delete files is DeleteObject [3].

[1] https://cloud.google.com/appengine/docs/go/storage#google_cloud_storage

[2] https://cloud.google.com/appengine/docs/go/googlecloudstorageclient/getstarted

[3] http://godoc.org/google.golang.org/cloud/storage#DeleteObject