merged(merged) {
        return new ArgHandler('Range.merged')
            .case(() => {
                return this.sheet().merged(this.address());
            })
            .case('*', merged => {
                this.sheet().merged(this.address(), merged);
                return this;
            })
            .handle(arguments);
    }
Sets a value indicating whether the cells in the range should be merged.
@param {boolean} merged - True to merge, false to unmerge.
@returns {Range} The range.