previousVisibleSiblingNode() {
        const context = (this.hasParent() ? this.getParent().children : this._tree.nodes());
        const i = findIndex(context, { id: this.id });

        return findLast(slice(context, 0, i), node => node.visible());
    }
Find the previous visible sibling node.

@return {TreeNode} Node object, if any.