[Python] Sub Folders of S3 bucket - Bucket name must match the regex "^[a-zA-Z0-9.\-_]

I have below code to get the list of objects in the bucket, but it does not work for the sub folders of the S3.

import boto3

bucket_from = "BucketSource"
s3 = boto3.resource('s3')
src = s3.Bucket(bucket_from)

for archive in src.objects.all():
print(archive.key)


While using sub folders, FirstLevelS3/SecondLevelS3/BucketSource, this is the error:

Bucket name must match the regex "^[a-zA-Z0-9.\-_]

Continue reading...