code: def package_existent(name):
      
      try:
          response = requests.get(PYPI_URL.format(name))
          if response.ok:
              msg = ('[error] "{0}" is registered already in PyPI.\n'
                     '\tSpecify another package name.').format(name)
              raise Conflict(msg)
      except (socket.gaierror,
              Timeout,
              ConnectionError,
              HTTPError) as exc:
          raise BackendFailure(exc)
docs: Search package.
  
      * :class:`bootstrap_py.exceptions.Conflict` exception occurs
        when user specified name has already existed.
  
      * :class:`bootstrap_py.exceptions.BackendFailure` exception occurs
        when PyPI service is down.
  
      :param str name: package name