You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: extensions.go
    path of file: ./repos/faas-netes/vendor/github.com/google/gnostic-models/extensions
    
    the code of the file until where you have to start completion: // Copyright 2017 Google LLC. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//    http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package gnostic_extension_v1

import (
	"io/ioutil"
	"log"
	"os"

	"google.golang.org/protobuf/proto"
	"google.golang.org/pro
    
func Main(handler extensionHandler) {
	// unpack the request
	data, err := ioutil.ReadAll(os.Stdin)
	if err != nil {
		log.Println("File error:", err.Error())
		os.Exit(1)
	}
	if len(data) == 0 {
		log.Println("No input data.")
		os.Exit(1)
	}
	request := &ExtensionHandlerRequest{}
	err = proto.Unmarshal(data, request)
	if err != nil {
		log.Println("Input error:", err.Error())
		os.Exit(1)
	}
	// call the handler
	handled, output, err := handler(request.Wrapper.ExtensionName, request.Wrapper.Yaml)
	// respond with the output of the handler
	response := &ExtensionHandlerResponse{
		Handled: false, // default assumption
		Errors:  make([]string, 0),
	}
	if err != nil {
		response.Errors = append(response.Errors, err.Error())
	} else if handled {
		response.Handled = true
		response.Value, err = anypb.New(output)
		if err != nil {
			response.Errors = append(response.Errors, err.Error())
		}
	}
	responseBytes, _ := proto.Marshal(response)
	os.Stdout.Write(responseBytes)
}