range(...ranges) {
        let value = '';

        for (let i = 1; i < ranges.length; i += 2) {
            const from = VerbalExpression.sanitize(ranges[i - 1]);
            const to = VerbalExpression.sanitize(ranges[i]);

            value += `${from}-${to}`;
        }

        return this.add(`[${value}]`);
    }
Matching any character within a range of characters
Usage: .range( from, to [, from, to ... ] )
@param {...string} ranges characters denoting beginning and ending of ranges
@returns {VerbalExpression} recompiled instance of VerbalExpression
@memberof VerbalExpression