def _list(keys):
    if (keys is None):
        keys = [None]
    res = self._read_many_files('list', map(self._url, keys), recursive=True)
    for (s3prefix, s3url, size) in res:
        (yield (s3prefix, s3url, None, int(size)))
def _list(keys):
    if (keys is None):
        keys = [None]
    res = self._read_many_files('list', map(self._url, keys), recursive=True)
    for (s3prefix, s3url, size) in res:
        (yield (s3prefix, s3url, None, int(size)))