title: Cannot set property 'round' of undefined in ejs
body: <p>I am learning nodejs from "secrete of ninja" book.
  I have an ejs program which I copied from book to run but it showing following error while I don't make any change in the program.</p>
  
  <p>This is an error:</p>
  
  <pre><code>ejs.filters.round = function(number, decimalPlaces) {
                 ^ 
   Cannot set property 'round' of undefined
  </code></pre>
  
  <p>I have this code:</p>
  
  <pre><code> var ejs = require('ejs');
   var template = '&lt;%=: price * 1.145 | round:2 %&gt;';
   var context = {price: 21};
  
  
  ejs.filters.round = function(number, decimalPlaces) {
  
  number = isNaN(number) ? 0 : number;
  decimalPlaces = !decimalPlaces ? 0 : decimalPlaces;
  
  var multiple = Math.pow(10, decimalPlaces);
  return Math.round(number * multiple) / multiple;
  };
  
  console.log(ejs.render(template, context));
  </code></pre>
  
  <p>can anybody suggest me where am I wrong?</p>