code: function(index, placeholder) {
      if (typeof this.config.indexes[index] === 'undefined') {
        console.log('LUNR: getLunrSearchPage will not work unless you specify a valid index from plugins.lunr.indexes in your Docpad configuration file.');
        return;
      }
      placeholder = placeholder || 'Search terms';
      var scriptElements = '';
      var dataFilename = this.config.indexes[index].indexFilename;
      var scripts = ['lunr.min.js', dataFilename, 'lunr-ui.min.js'];
      for (var i in scripts) {
        scriptElements += '<script src="/lunr/' + scripts[i] +
          '" type="text/javascript"></script>';
      }
      return '<input type="text" class="search-bar" id="lunr-input" placeholder="' + placeholder + '" />' +
        '<input type="hidden" id="lunr-hidden" />' +
        scriptElements;
    }
docs: some helper functions we'll provide to the template