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: cert.go
    path of file: ./repos/arvados/lib/selfsigned
    
    the code of the file until where you have to start completion: // Copyright (C) The Arvados Authors. All rights reserved.
//
// SPDX-License-Identifier: AGPL-3.0

package selfsigned

import (
	"crypto/rand"
	"crypto/rsa"
	"crypto/tls"
	"crypto/x509"
	"crypto/x509/pkix"
	"fmt"
	"math/big"
	"net"
	"time"
)

type CertGenerator struct {
	Bits  int
	Hosts []string
	IsCA  bool
}

func (gen CertGenerator) Generate() (cert tls.Certificate, err error) {
	keyUsage := x509.KeyUsageDigitalSignature | x509.KeyUsageKeyEncipherment
	if gen.IsCA {
		keyUsage |= x509.KeyUsageCertSign
	}
	notBefore := time.Now()
	notAfter := time.Now().Add(time.Hour * 24 * 365)
	snMax := new(big.Int).Lsh(big.NewInt(1), 128)
	sn, err := rand.Int(rand.Reader, snMax)
	if err != nil {
		err = fmt.Errorf("Failed to generate serial number: %w", err)
		return
	}
	template := x509.Certificate{
		SerialNumber: sn,
		Subject: pkix.Name{
			Organization: []string{"N/A"},
		},
		NotBefore:             notBefore,
		NotAfter:              notAfter,
		KeyUsage:              keyUsage,
		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
		Bas
    
func (gen CertGenerator) Generate() (cert tls.Certificate, err error) {
	keyUsage := x509.KeyUsageDigitalSignature | x509.KeyUsageKeyEncipherment
	if gen.IsCA {
		keyUsage |= x509.KeyUsageCertSign
	}
	notBefore := time.Now()
	notAfter := time.Now().Add(time.Hour * 24 * 365)
	snMax := new(big.Int).Lsh(big.NewInt(1), 128)
	sn, err := rand.Int(rand.Reader, snMax)
	if err != nil {
		err = fmt.Errorf("Failed to generate serial number: %w", err)
		return
	}
	template := x509.Certificate{
		SerialNumber: sn,
		Subject: pkix.Name{
			Organization: []string{"N/A"},
		},
		NotBefore:             notBefore,
		NotAfter:              notAfter,
		KeyUsage:              keyUsage,
		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
		BasicConstraintsValid: true,
		IsCA:                  gen.IsCA,
	}
	for _, h := range gen.Hosts {
		if ip := net.ParseIP(h); ip != nil {
			template.IPAddresses = append(template.IPAddresses, ip)
		} else {
			template.DNSNames = append(template.DNSNames, h)
		}
	}
	bits := gen.Bits
	if bits == 0 {
		bits = 4096
	}
	priv, err := rsa.GenerateKey(rand.Reader, bits)
	if err != nil {
		err = fmt.Errorf("error generating key: %w", err)
		return
	}
	certder, err := x509.CreateCertificate(rand.Reader, &template, &template, &priv.PublicKey, priv)
	if err != nil {
		err = fmt.Errorf("error creating certificate: %w", err)
		return
	}
	cert = tls.Certificate{
		Certificate: [][]byte{certder},
		PrivateKey:  priv,
	}
	return
}