docs: function onDataFetch(query, resolve) {
      let output = [];
  
      query.forEach(function(query) {
          let filteredItems = data.filter(function(obj) {
              return obj.parent === query.parent;
          });
  
          output.push({
              parent: query.parent,
              items: filteredItems.splice(query.offset, query.limit)
          });
  
      });
  
      resolve(JSON.parse(JSON.stringify(output)));
  }