download s3

def downLoadImage(region, imageObj):
    s3 = boto3.resource('s3', region_name=region)
    bucketName = str(imageObj["Bucket"])
    objectName = str(imageObj["Object"])
    key = s3.Bucket(bucketName) \
             .Object(objectName)
    saveFileName = '/tmp/'+objectName.replace('/', '__')
    s3.meta.client.download_file(bucketName, objectName, saveFileName)
    return saveFileName