code: function cloneItree(itree, excludeKeys) {
      const clone = {};
      excludeKeys = _.castArray(excludeKeys);
      excludeKeys.push('ref');
  
      _.each(itree, (v, k) => {
          if (!_.includes(excludeKeys, k)) {
              clone[k] = _.cloneDeep(v);
          }
      });
  
      return clone;
  }
docs: Helper method to clone an ITree config object.
  
  Rejects non-clonable properties like ref.
  
  @private
  @param {object} itree ITree configuration object
  @param {array} excludeKeys Keys to exclude, if any
  @return {object} Cloned ITree.