code: function () {
                  var me = this;
                  if (!me._dataInPromise) {
                      me._dataInPromise = new Promise(function (resolve) {
                          me._dataInResolve = resolve;
                      }).then(function (data) {
                          delete me._dataInPromise;
                          delete me._dataInResolve;
                          return data;
                      });
                  }
                  return me._dataInPromise;
              }
docs: Wait until data was written to this stream
  
  @return {Promise} Resolved when a data as been written to this stream
  @since 0.2.5