code: function(list_data, item_data) {
    return (list_data.type === item_data.type &&
            list_data.delimiter === item_data.delimiter &&
            list_data.bullet_char === item_data.bullet_char);
  }
docs: Returns true if the two list items are of the same type, with the same delimiter and bullet character.  This is used in agglomerating list items into lists.