code: func negativeScaleInt64(base int64, scale Scale) (result int64, exact bool) {
  	if scale == 0 {
  		return base, true
  	}
  
  	value := base
  	var fraction bool
  	for i := Scale(0); i < scale; i++ {
  		if !fraction && value%10 != 0 {
  			fraction = true
  		}
  		value = value / 10
  		if value == 0 {
  			if fraction {
  				if base > 0 {
  					return 1, false
  				}
  				return -1, false
  			}
  			return 0, true
  		}
  	}
  	if fraction {
  		if base > 0 {
  			value += 1
  		} else {
  			value += -1
  		}
  	}
  	return value, !fraction
  }
docs: // negativeScaleInt64 reduces base by the provided scale, rounding up, until the
  // value is zero or the scale is reached. Passing a negative scale is undefined.
  // The value returned, if not exact, is rounded away from zero.