How to implement BarFunnel into chartjs-node

I have tried to require BarFunnel.js as
require('./plugins/chart.barfunnel');

but I am getting following error

`ReferenceError: Chart is not defined
at Object. (D:\RacDevelopment\Nodejs\chartsservice\src\charts\plugins\chart.barfunnel.js:195:15)
at Module._compile (module.js:652:30)
at Object.Module._extensions..js (module.js:663:10)
at Module.load (module.js:565:32)
at tryModuleLoad (module.js:505:12)
at Function.Module._load (module.js:497:3)
at Module.require (module.js:596:17)
at require (internal/module.js:11:18)
at Object. (D:\RacDevelopment\Nodejs\chartsservice\src\charts\index.js:5:1)
at Module._compile (module.js:652:30)
at Object.Module._extensions..js (module.js:663:10)
at Module.load (module.js:565:32)
at tryModuleLoad (module.js:505:12)
at Function.Module._load (module.js:497:3)
at Module.require (module.js:596:17)
at require (internal/module.js:11:18)`

any solution to this?