datetime.datetime end: publication time to end with
:param str cache_to: directory to cache archives into, if an archive is
  available here it is not downloaded
:param bool bridge: standard descriptors if **False**, bridge if **True**
:param int timeout: timeout for downloading each individual archive when
  the connection becomes idle, no timeout applied if **None**
:param int retries: maximum attempts to impose on a per-archive basis

:returns: **iterator** of
  :class:`~stem.descriptor.server_descriptor.ServerDescriptor` for the
  given time range

:raises: :class:`~stem.DownloadFailed` if the download fails
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