func NewReader(rand *rand.Rand, bytes int64) io.Reader {
	return &reader{
		rand:  rand,
		bytes: bytes,
	}
}
func NewReader(rand *rand.Rand, bytes int64) io.Reader {
	return &reader{
		rand:  rand,
		bytes: bytes,
	}
}
// NewReader returns a Reader which generates strings of characters.