title: how to call functions recursively in async.waterfall?
body: <pre><code>async.waterfall([
      function(callback) {
          callback(null, 'one', 'two');
      },
      function(arg1, arg2, callback) {
        // arg1 now equals 'one' and arg2 now equals 'two'
          callback(null, 'three');
      },
      function(arg1, callback) {
          // arg1 now equals 'three'
          callback(null, 'done');
      }
  ], function (err, result) {
      // result now equals 'done'
  });
  </code></pre>
  
  <p>Beginner here, just wondering. I need to call functions 2 and 3 recursively depending on the output of function 3. Would a async.doWhilst work if I put functions 2 and 3 in one async.series function? </p>