$(...).accordion is not a function

[ThePieMonster]

Noticed this project seems pretty old.
If it is no longer supported please mark it as archived.

Uncaught TypeError: $(...).accordion is not a function
    at HTMLDocument.<anonymous> (index.html:108)
    at j (jquery-2.1.4.min.js:2)
    at Object.fireWith [as resolveWith] (jquery-2.1.4.min.js:2)
    at Function.ready (jquery-2.1.4.min.js:2)
    at HTMLDocument.I (jquery-2.1.4.min.js:2)