s3_downloader.py

import boto3

prefix = ""
bucket = ""

client = boto3.client('s3')
paginator = client.get_paginator('list_objects')
operation_parameters = {'Bucket': bucket,
                        'Prefix': prefix}
page_iterator = paginator.paginate(**operation_parameters)
for page in page_iterator:
    keys = page['Contents']
    for key in keys:
    	print key['Key']
    	client.download_file(bucket, key['Key'], key['Key'].replace('/', '-'))