AWS Developer Training Python Lambda

from __future__ import print_function

import json
import urllib
import boto3
import csv
import StringIO

print('Loading function')

s3 = boto3.client('s3')

transform_bucket = 'jamesfoo456'

def lambda_handler(event, context):
    print("Received event: " + json.dumps(event, indent=2))

    # Get the object from the event and show its content type
    bucket = event['Records'][0]['s3']['bucket']['name']
    key = urllib.unquote_plus(event['Records'][0]['s3']['object']['key']).decode('utf8')
    try:
        response = s3.get_object(Bucket=bucket, Key=key)
        body = response['Body'].read()
        file_obj = StringIO.StringIO(body)
        records = json.dumps([row for row in csv.DictReader(file_obj)])
        boto3.resource('s3').Object(transform_bucket, key.replace('.txt', '.json')).put(Body=records)
        return 'OK'
    except Exception as e:
        print(e)
        print('Error getting object {} from bucket {}. Make sure they exist and your bucket is in the same region as this function.'.format(key, bucket))
        raise e