code: function groupDelta(nodes, callback) {
    async.eachLimit(nodes, 10, (node, cb) => {
      if(node.path === null) {
        // if node.path is null we have to skip the node
        logger.info('Remote Delta: Got node with path equal null', {node});
        return cb(null);
      }
  
      const query = {remoteId: node.id, path: node.path};
      ignoreDb.isIgnoredNode(query, (err, isIgnored) => {
        if(err) return cb(err);
        if(isIgnored) return cb(null);
  
        groupNode(node);
        cb(null);
      });
    }, callback);
  }
docs: groups the delta by node id, ignores paths found in ignoreDb
  
  @param {Array} nodes - array of node actions (data.nodes from api call)
  @param {Function} callback - callback function
  @returns {void} - no return value