WeChat.WebPage.sign_jssdk

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

sign_jssdk(jsapi_ticket, url, appid)

Specs

sign_jssdk(js_api_ticket(), url(), WeChat.appid()) :: js_sdk_config()

生成JS-SDK配置(by ticket) - 官方文档