Method by

src/main/java/groovy/lang/NumberRange.java:243–248

For a NumberRange with step size 1, creates a new NumberRange with the same from and to as this NumberRange but with a step size of stepSize . @param stepSize the desired step size @return a new NumberRange

(T stepSize)

     * @return a new NumberRange
     */
    public <T extends Number & Comparable> NumberRange by(T stepSize) {
        if (!Integer.valueOf(1).equals(this.stepSize)) {
            throw new IllegalStateException("by only allowed on ranges with original stepSize = 1 but found " + this.stepSize);
        }
        return new NumberRange(comparableNumber(from), comparableNumber(to), stepSize, inclusiveLeft, inclusiveRight);
    }

    /**
     * Casts the supplied comparable to a comparable number.