code: function send(callback) {
      if (callback) {
        this.on('complete', function (resp) {
          callback.call(resp, resp.error, resp.data);
        });
      }
      this.runTo();
  
      return this.response;
    }
docs: @!group Sending a Request
   
  @overload send(callback = null)
  Sends the request object.
  
  @callback callback function(err, data)
  If a callback is supplied, it is called when a response is returned
  from the service.
  @param err [Error] the error object returned from the request.
  Set to `null` if the request is successful.
  @param data [Object] the de-serialized data returned from
  the request. Set to `null` if a request error occurs.
  @example Sending a request with a callback
  request = client.listTable({Bucket: 'bucket', Key: 'key'});
  request.send(function(err, data) { console.log(err, data); });