code: def get_sources(arxiv_id):
      
      try:
          request = requests.get(ARXIV_EPRINT_URL.format(arxiv_id=arxiv_id))
          request.raise_for_status()
          file_object = io.BytesIO(request.content)
          return tarfile.open(fileobj=file_object)
      except (RequestException, AssertionError, tarfile.TarError):
          return None
docs: Download sources on arXiv for a given preprint.
  
      .. note::
  
          Bulk download of sources from arXiv is not permitted by their API. \
                  You should have a look at http://arxiv.org/help/bulk_data_s3.
  
      :param eprint: The arXiv id (e.g. ``1401.2910`` or ``1401.2910v1``) in a \
              canonical form.
      :returns: A ``TarFile`` object of the sources of the arXiv preprint or \
              ``None``.