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: update_key_add_rotation.go
    path of file: ./repos/golang-samples/kms
    
    the code of the file until where you have to start completion: // Copyright 2020 Google LLC
//
// 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
//
//     https://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 kms

// [START kms_update_key_add_rotation_schedule]
import (
	"context"
	"fmt"
	"io"
	"time"

	kms "cloud.google.com/go/kms/apiv1"
	"cloud.google.com/go/kms/apiv1/kmspb"
	fieldmask "google.golang.org/genproto/protobuf/field_mask"
	"google.golang.
    
func addRotationSchedule(w io.Writer, name string) error {
	// name := "projects/my-project/locations/us-east1/keyRings/my-key-ring/cryptoKeys/my-key"

	// Create the client.
	ctx := context.Background()
	client, err := kms.NewKeyManagementClient(ctx)
	if err != nil {
		return fmt.Errorf("failed to create kms client: %w", err)
	}
	defer client.Close()

	// Build the request.
	req := &kmspb.UpdateCryptoKeyRequest{
		CryptoKey: &kmspb.CryptoKey{
			// Provide the name of the key to update
			Name: name,

			// Rotate the key every 30 days
			RotationSchedule: &kmspb.CryptoKey_RotationPeriod{
				RotationPeriod: &durationpb.Duration{
					Seconds: int64(60 * 60 * 24 * 30), // 30 days
				},
			},

			// Start the first rotation in 24 hours
			NextRotationTime: &timestamppb.Timestamp{
				Seconds: time.Now().Add(24 * time.Hour).Unix(),
			},
		},
		UpdateMask: &fieldmask.FieldMask{
			Paths: []string{"rotation_period", "next_rotation_time"},
		},
	}

	// Call the API.
	result, err := client.UpdateCryptoKey(ctx, req)
	if err != nil {
		return fmt.Errorf("failed to update key: %w", err)
	}
	fmt.Fprintf(w, "Updated key: %s\n", result.Name)
	return nil
}