WeChat.UserTag.batch_tagging_users

You're seeing just the function batch_tagging_users, go back to WeChat.UserTag module for more information.
Link to this function

batch_tagging_users(client, id, openid_list)

Specs

batch_tagging_users(WeChat.client(), tag_id(), WeChat.openid_list()) ::
  WeChat.response()

批量为用户打标签 - 官方文档