def _list(keys):
    if (keys is None):
        keys = [None]
    urls = ((self._url(key).rstrip('/') + '/') for key in keys)
    res = self._read_many_files('list', urls)
    for (s3prefix, s3url, size) in res:
        if size:
            (yield (s3prefix, s3url, None, int(size)))
        else:
            (yield (s3prefix, s3url, None, None))
def _list(keys):
    if (keys is None):
        keys = [None]
    urls = ((self._url(key).rstrip('/') + '/') for key in keys)
    res = self._read_many_files('list', urls)
    for (s3prefix, s3url, size) in res:
        if size:
            (yield (s3prefix, s3url, None, int(size)))
        else:
            (yield (s3prefix, s3url, None, None))