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: DynamoDBUpdateItem.go
    path of file: ./repos/aws-doc-sdk-examples/go/example_code/dynamodb
    
    the code of the file until where you have to start completion: // Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
// snippet-start:[dynamodb.go.update_item]
package main

// snippet-start:[dynamodb.go.update_item.imports]
import (
	"github.com/aws/aws-sdk-go/aws"
	"github.com/aws/aws-sdk-go/aws/session"
	"github.com/aws/aws-sdk-go/service/dynamodb"

	"fmt"
	"log"
)

// snippet-end:[dynamodb.go.update_item.i
    
func main() {
	// snippet-start:[dynamodb.go.update_item.session]
	// Initialize a session that the SDK will use to load
	// credentials from the shared credentials file ~/.aws/credentials
	// and region from the shared configuration file ~/.aws/config.
	sess := session.Must(session.NewSessionWithOptions(session.Options{
		SharedConfigState: session.SharedConfigEnable,
	}))

	// Create DynamoDB client
	svc := dynamodb.New(sess)
	// snippet-end:[dynamodb.go.update_item.session]

	// snippet-start:[dynamodb.go.update_item.call]
	// Update item in table Movies
	tableName := "Movies"
	movieName := "The Big New Movie"
	movieYear := "2015"
	movieRating := "0.5"

	input := &dynamodb.UpdateItemInput{
		ExpressionAttributeValues: map[string]*dynamodb.AttributeValue{
			":r": {
				N: aws.String(movieRating),
			},
		},
		TableName: aws.String(tableName),
		Key: map[string]*dynamodb.AttributeValue{
			"Year": {
				N: aws.String(movieYear),
			},
			"Title": {
				S: aws.String(movieName),
			},
		},
		ReturnValues:     aws.String("UPDATED_NEW"),
		UpdateExpression: aws.String("set Rating = :r"),
	}

	_, err := svc.UpdateItem(input)
	if err != nil {
		log.Fatalf("Got error calling UpdateItem: %s", err)
	}

	fmt.Println("Successfully updated '" + movieName + "' (" + movieYear + ") rating to " + movieRating)
	// snippet-end:[dynamodb.go.update_item.call]
}