code: function queryUserInfo(parentSpan, username, callback) {
      // Aggregated user information across multiple API calls
      var user = {
          login        : null,
          type         : null,
          repoNames    : [],
          recentEvents : 0,
          eventCounts  : {},
      };
  
      // Call the callback only when all three API requests finish or on the
      // first error.
      var remainingCalls = 3;
      var next = function (err) {
          // Early terminate on any error
          remainingCalls -= err ? Math.max(remainingCalls, 1) : 1;
          if (remainingCalls === 0) {
              callback(err, err ? null : user);
          }
      };
  
      // First query the user info for the given username
      httpGet(parentSpan, 'http://api.github.com/users/' + username, function (err, json) {
          if (err) {
              return next(err);
          }
          user.login = json.login;
          user.type  = json.type;
  
          // Use the user info to query names of all the user's public repositories
          httpGet(parentSpan, json.repos_url, function (err, json) {
              if (err) {
                  return next(err);
              }
              for (var i = 0; i < json.length; i++) {
                  user.repoNames.push(json[i].name);
              }
              next(null);
          });
  
          // In parallel, query the recent events activity for the user
          httpGet(parentSpan, json.received_events_url, function (err, json) {
              if (err) {
                  return next(err);
              }
              user.recentEvents = json.length;
              for (var i = 0; i < json.length; i++) {
                  var eventType = json[i].type;
                  user.eventCounts[eventType] = user.eventCounts[eventType] || 0;
                  user.eventCounts[eventType]++;
              }
              next(null);
          });
  
          next(null);
      });
  }
docs: Make a series GitHub calls and aggregate the data into the `user` object
  defined below.