code: def backend_version(backend, childprocess=None):
      
      if childprocess is None:
          childprocess = childprocess_default_value()
      if not childprocess:
          return _backend_version(backend)
      else:
          return run_in_childprocess(_backend_version, None, backend)
docs: Back-end version.
  
      :param backend: back-end (examples:scrot, wx,..)
      :param childprocess: see :py:func:`grab`
      :return: version as string