code: func IndexOfDifference(str1 string, str2 string) int {
  	if str1 == str2 {
  		return INDEX_NOT_FOUND
  	}
  	if IsEmpty(str1) || IsEmpty(str2) {
  		return 0
  	}
  	var i int
  	for i = 0; i < len(str1) && i < len(str2); i++ {
  		if rune(str1[i]) != rune(str2[i]) {
  			break
  		}
  	}
  	if i < len(str2) || i < len(str1) {
  		return i
  	}
  	return INDEX_NOT_FOUND
  }
docs: /*
  IndexOfDifference compares two strings, and returns the index at which the strings begin to differ.
  
  Parameters:
      str1 - the first string
      str2 - the second string
  
  Returns:
      the index where str1 and str2 begin to differ; -1 if they are equal
  */