uncheck(shallow) {
        this._tree.batch();

        // Will we apply this state change to our children?
        const deep = !shallow && this._tree.config.checkbox.autoCheckChildren;

        baseStateChange('checked', false, 'unchecked', this, deep);

        // Reset indeterminate state
        this.state('indeterminate', false);

        // Refresh our parent
        if (this.hasParent()) {
            this.getParent().refreshIndeterminateState();
        }

        this._tree.end();

        return this;
    }
Uncheck this node.

@param {boolean} shallow Skip auto-unchecking children.
@return {TreeNode} Node object.