code: function(path, callback) {
              this.update();
              var out = fs.createWriteStream(path),
                  stream = this._element.createPNGStream();
              // Pipe the png stream to the write stream:
              stream.pipe(out);
              if (callback) {
                  out.on('close', callback);
              }
              return out;
          }
docs: DOCS: CanvasView#exportImage(path, callback);