copy(dest, hierarchy, includeState) {
        if (!dest || !isFunction(dest.addNode)) {
            throw new Error('Destination must be an Inspire Tree instance.');
        }

        let node = this;
        if (hierarchy) {
            node = node.copyHierarchy(false, includeState);
        }

        return dest.addNode(cloneDeep(node.toObject(false, includeState)));
    }
Copy node to another tree instance.

@param {object} dest Destination Inspire Tree.
@param {boolean} hierarchy Include necessary ancestors to match hierarchy.
@param {boolean} includeState Include itree.state object.
@return {object} Property "to" for defining destination.