set(columnToSet, value) {
        const newRow = Object.assign({}, this[__values__], {
            [columnToSet]: value
        });
        return this.__newInstance__(newRow, Object.keys(newRow));
    }
Set a Row value by its column, or create a new value if column doesn't exist.
@param {String} columnToSet The column value to set.
@returns {Row} A new Row with the modified / new value.
@example
row.set('column1', 6)