code: func isBetween(lowStr, highStr, xStr string) bool {
  	low := bigIntFromStr(lowStr, 10)
  	high := bigIntFromStr(highStr, 10)
  	x := bigIntFromStr(xStr, 10)
  	return x.Cmp(low) == 1 && x.Cmp(high) == -1
  }
docs: // Takes two large base 10 numeric strings low and high and returns low < x < high.