에러원인을 모르겠어요

node app을 했더니 이런 에러가 났는데 원인을 모르겟어요

D:\005_Study\React\react-nodebird\prepare\back\models\comment.js:16

    db.Comment.belognsTo(db.Post);

               ^

TypeError: db.Comment.belognsTo is not a function

    at Function.Comment.associate (D:\005_Study\React\react-nodebird\prepare\back\models\comment.js:16:16)

    at D:\005_Study\React\react-nodebird\prepare\back\models\index.js:19:19

    at Array.forEach ()

    at Object. (D:\005_Study\React\react-nodebird\prepare\back\models\index.js:17:17)

    at Module._compile (internal/modules/cjs/loader.js:1138:30)

    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1158:10)

    at Module.load (internal/modules/cjs/loader.js:986:32)

    at Function.Module._load (internal/modules/cjs/loader.js:879:14)

    at Module.require (internal/modules/cjs/loader.js:1026:19)

    at require (internal/modules/cjs/helpers.js:72:18)