next() is not a function unable to use generators in NodeJS

I am using the following code in NodeJS 7.10.0:

function * gen(){
    yield 100;
    yield 200;
    yield 300
}
console.log(gen.next());

and I get this in return:

TypeError: gen.next is not a function
    at Object.<anonymous> (/Files/development/learning/node-bits/generators.js:15:17)
    at Module._compile (module.js:571:32)
    at Object.Module._extensions..js (module.js:580:10)
    at Module.load (module.js:488:32)
    at tryModuleLoad (module.js:447:12)
    at Function.Module._load (module.js:439:3)
    at Module.runMain (module.js:605:10)
    at run (bootstrap_node.js:427:7)
    at startup (bootstrap_node.js:151:9)
    at bootstrap_node.js:542:3

via quinton