WeChat.CustomService.add_kf_account

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

add_kf_account(client, kf_account, nickname, password)

Specs

add_kf_account(WeChat.client(), kf_account(), nickname(), password()) ::
  WeChat.response()

添加客服帐号 - 官方文档

每个公众号最多添加100个客服账号。