def __init__(self, prefix, version=CURRENT_VERSION):
        self.VERSION = version

        url_tup = urlparse(prefix)

        if SUPPORTED_STORE_SCHEMES not in url_tup.scheme:
            raise wal_e.exception.UserException(
                msg='bad S3, Windows Azure Blob Storage, or OpenStack Swift '
                    'URL scheme passed',
                detail=('The scheme {0} was passed when "s3", "wabs", or '
                        '"swift" was expected.'.format(url_tup.scheme)))

        for scheme in SUPPORTED_STORE_SCHEMES:
            setattr(self, 'is_%s' % scheme, scheme == url_tup.scheme)

        self._url_tup = url_tup

        # S3 api requests absolutely cannot contain a leading slash.
        api_path_prefix = url_tup.path.lstrip('/')

        # Also canonicalize a trailing slash onto the prefix, should
        # none already exist. This only applies if we actually have a
        # prefix, i.e., our objects are not being created in the bucket's
        # root.
        if api_path_prefix and api_path_prefix[-1] != '/':
            self._api_path_prefix = api_path_prefix + '/'
            self._api_prefix = prefix + '/'
        else:
            self._api_path_prefix = api_path_prefix
            self._api_prefix = prefix
dataset/ETHPy150Open wal-e/wal-e/wal_e/storage/base.py/StorageLayout.__init__/swapped operands of `not in`