How to use domains to handle exception in node js app

In my node js app i want to catch the exception using domains.How can i do this.I have tried the below example but it showing error as 'Error: Cannot find module 'step''..

app.js

            var domain=require('domain');
            var mainDomain = domain.create();
            mainDomain.run(function() {
            fs.readFile(filename, 'utf8', mainDomain.intercept(function(data) {
               console.log(data);      
            }));               
             });
            mainDomain.on("error", function(error){
               console.log(error);
            });