docs: def start_server_background(port):
      """Start the newtab server as a background process."""
  
      if sys.version_info[0] == 2:
          lines = ('import pydoc\n'
                   'pydoc.serve({port})')
          cell = lines.format(port=port)
      else:
          # The location of newtabmagic (normally $IPYTHONDIR/extensions)
          # needs to be added to sys.path.
          path = repr(os.path.dirname(os.path.realpath(__file__)))
          lines = ('import sys\n'
                   'sys.path.append({path})\n'
                   'import newtabmagic\n'
                   'newtabmagic.pydoc_cli_monkey_patched({port})')
          cell = lines.format(path=path, port=port)
  
      # Use script cell magic so that shutting down IPython stops
      # the server process.
      line = "python --proc proc --bg --err error --out output"
      ip = get_ipython()
      ip.run_cell_magic("script", line, cell)
  
      return ip.user_ns['proc']