code: function emitStart(name, attrs) {
    this.emit('data', '<' + name);
    for (var attr in attrs) if (__own.call(attrs, attr)) {
      this.emit('data', ' ' + attr + '="' + escape(attrs[attr]) + '"');
    }
    this.emit('data', '>');
  }
docs: Emits XML for element opening tag.