$ node --version
v5.10.1
$ node
> var Combinatorics = require('js-combinatorics');
undefined
> var cmb, a;
undefined
> cmb = Combinatorics.power(['a','b','c']);
[Number: 8]
> cmb.each(function(a){ console.log(a) });
TypeError: cmb.each is not a function
    at repl:1:5
    at REPLServer.defaultEval (repl.js:269:27)
    at bound (domain.js:287:14)
    at REPLServer.runBound [as eval] (domain.js:300:12)
    at REPLServer.<anonymous> (repl.js:439:12)
    at emitOne (events.js:95:20)
    at REPLServer.emit (events.js:182:7)
    at REPLServer.Interface._onLine (readline.js:211:10)
    at REPLServer.Interface._line (readline.js:550:8)
    at REPLServer.Interface._ttyWrite (readline.js:827:14)