code: func round(num, denom *big.Int) {
  	r := new(big.Int)
  	num.DivMod(num, denom, r)
  
  	if r.Cmp(half) == 1 {
  		num.Add(num, big.NewInt(1))
  	}
  }
docs: // round sets num to num/denom rounded to the nearest integer.