func NewDummyDataGen(totalLength, skipOffset int64) io.ReadSeeker {
	if totalLength < 0 {
		panic("Negative length passed to DummyDataGen!")
	}
	if skipOffset < 0 {
		panic("Negative rotations are not allowed")
	}

	skipOffset %= int64(len(alphabets))
	const multiply = 100
	as := bytes.Repeat(alphabets, multiply)
	b := as[skipOffset : skipOffset+int64(len(alphabets)*(multiply-1))]
	return &DummyDataGen{