code: def get_client_class(api_name, version, version_map):
      
      try:
          client_path = version_map[str(version)]
      except (KeyError, ValueError):
          msg = _("Invalid %(api_name)s client version '%(version)s'. must be "
                  "one of: %(map_keys)s")
          msg = msg % {'api_name': api_name, 'version': version,
                       'map_keys': ', '.join(version_map.keys())}
          raise exceptions.UnsupportedVersion(msg)
  
      return importutils.import_class(client_path)
docs: Returns the client class for the requested API version.
  
      :param api_name: the name of the API, e.g. 'compute', 'image', etc
      :param version: the requested API version
      :param version_map: a dict of client classes keyed by version
      :rtype: a client class for the requested API version