next is not defined

[Kiranyellu]

/var/www/html/meanstacktutorial/app/models/user.js:17
next();
^

ReferenceError: next is not defined
at bcrypt.hash (/var/www/html/meanstacktutorial/app/models/user.js:17:9)
at /var/www/html/meanstacktutorial/node_modules/bcrypt-nodejs/bCrypt.js:631:3
at _combinedTickCallback (internal/process/next_tick.js:131:7)
at process._tickCallback (internal/process/next_tick.js:180:9)
please help me out ..thank you in advance

[Kiranyellu]