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: signature_generate.go
    path of file: ./repos/ethereum-development-with-go-book/code
    
    the code of the file until where you have to start completion: package main

import (
	"fmt"
	"log"

	"github.com/ethereum/go-ethereum/common/hexutil"
	"github.com/ethereum/go-ethereum/crypto"
)

func main() {
	privateKey, err := crypto.HexToECDSA("fad9c8855b740a0b7ed4c221dbad0f33a83a49cad6b3fe8d5817ac83d38b6a19")
	if err != nil {
		log.Fatal(err)
	}

	data := []byte("hello")
	hash := crypto.Keccak256Hash(data)
	fmt.Println(hash.He
    
func main() {
	privateKey, err := crypto.HexToECDSA("fad9c8855b740a0b7ed4c221dbad0f33a83a49cad6b3fe8d5817ac83d38b6a19")
	if err != nil {
		log.Fatal(err)
	}

	data := []byte("hello")
	hash := crypto.Keccak256Hash(data)
	fmt.Println(hash.Hex()) // 0x1c8aff950685c2ed4bc3174f3472287b56d9517b9c948127319a09a7a36deac8

	signature, err := crypto.Sign(hash.Bytes(), privateKey)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println(hexutil.Encode(signature)) // 0x789a80053e4927d0a898db8e065e948f5cf086e32f9ccaa54c1908e22ac430c62621578113ddbb62d509bf6049b8fb544ab06d36f916685a2eb8e57ffadde02301
}