dataValidation() {
        return new ArgHandler('Cell.dataValidation')
            .case(() => {
                return this.sheet().dataValidation(this.address());
            })
            .case('boolean', obj => {
                return this.sheet().dataValidation(this.address(), obj);
            })
            .case('*', obj => {
                this.sheet().dataValidation(this.address(), obj);
                return this;
            })
            .handle(arguments);
    }
Set or clear the data validation object of the cell.
@param {object|undefined} dataValidation - Object or null to clear.
@returns {Cell} The cell.