title: Add context to a Mongoose callback
body: <p>What is the correct way to add context to a callback used in a Model query? For example...</p>
  
  <pre><code>function doSomething(param) {
      var magic = function(context, err, results) {
          if(err) { console.log('fail'); }
          else {
              // do the magic with context and results
          }
      }
  
      for( var i=0; i &lt; 5; i++ ) {
          var myObject = {'secret' : i};
          MyModel.find({number:param[i]}, magic(myObject, err, results));
      }
  }
  </code></pre>
  
  <p>I'd like to loop through results for each query and have the context of myObject. The above solution does not work. 'err' and 'results' are not defined.</p>
  
  <p>I normally do this with an anonymous function, but I can't rely on the context inside the for loop.</p>