title: callback undefined in async.waterfall method
body: <p>From the below code i'm not getting result1 data. It's undefined. Can somebody help me? </p>
  
  <pre><code>async.waterfall([
      function(callback) {
          request({
              method: 'GET',
              headers: {
                  'Content-Type': 'application/json'
              },
              url: url
          }, function(error, response, body) {
              if (error) {
                  callback(error);
              } else {
                  var result = JSON.parse(body);
                  callback(null, result); //sending to next function
              }
          });
      },
      function(result, callback) {
  
          async.eachSeries(result, function(item, callback) {
              request({
                  method: 'GET',
                  headers: {
                      'Content-Type': 'application/json'
                  },
                  url: url+item.id
              }, function(error, response, body) {
                  if (error) {
                      callback(error);
                  } else {
                      var result1 = JSON.parse(body);
                      callback(null, result1);
                  }
              });
          }, function(err, result1) {
              if (!err) {
                  callback(null, result1);
              } else {
                  callback(err);
              }
          });
      },
      function(result1, callback) {
        console.log(result1);  // getting undefined
          request({
              method: 'GET',
              headers: {
                  'Content-Type': 'application/json'
              },
              url: url
          }, function(error, response, body) {
              if (error) {
                  callback(error);
              } else {
                  var result2 = JSON.parse(body);
                  callback(null, result2);
              }
          });
      }
  ], function(error, res) {
      console.log(res); // process final result
  });
  </code></pre>