int bTwos = Long.numberOfTrailingZeros(b);
    b >>= bTwos; // divide out all 2s
    while (a != b) { // both a, b are odd
      // The key to the binary GCD algorithm is as follows:
      // Both a and b are odd. Assume a > b; then gcd(a - b, b) = gcd(a, b).
      // But in gcd(a - b, b), a - b is even and b is odd, so we can divide out powers of two.

      // We bend over backwards to avoid branching, adapting a technique from

// all the ellipses sizes.
func getDivisibleSize(totalSizes []uint64) (result uint64) {
	gcd := func(x, y uint64) uint64 {
		for y != 0 {
			x, y = y, x%y
		}
		return x
	}
	result = totalSizes[0]
	for i := 1; i < len(totalSizes); i++ {
		result = gcd(result, totalSizes[i])
	}
	return result
}

// isValidSetSize - checks whether given count is a valid set size for erasure coding.