code: function updateNode(node, callback) {
    syncDb.update(node._id, node, (err, result) => {
      if(err) return callback(err);
  
      callback(null, node);
    });
  }
docs: Updates a node in the database
  
  @param {Object} node - database node to update
  @param {Function} callback - callback function
  @returns {void} - no return value