<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _s3_path_split(s3_path):
 """ Split an S3 path into bucket and key. Parameters s3_path : str Returns ------- splitted : (str, str) (bucket, key) Examples -------- S3Path(bucket_name='my-bucket', key='foo/bar.jpg') """

    if not s3_path.startswith('s3://'):
        raise ValueError('s3_path is expected to start with \'s3://\', '
                         'but was {}'.format(s3_path))
    bucket_key = s3_path[len('s3://'):]
    bucket_name, key = bucket_key.split('/', 1)
    return S3Path(bucket_name, key)