code: def addStrings(self, num1, num2):
      res = []
      pos1 = len(num1) - 1
      pos2 = len(num2) - 1
      carry = 0
      # This conditon is great
      # https://leetcode.com/problems/add-strings/discuss/90436/Straightforward-Java-8-main-lines-25ms
      while pos1 >= 0 or pos2 >= 0 or carry == 1:
          digit1 = digit2 = 0
          if pos1 >= 0:
              digit1 = ord(num1[pos1]) - ord("0")
          if pos2 >= 0:
              digit2 = ord(num2[pos2]) - ord("0")
          res.append(str((digit1 + digit2 + carry) % 10))
          carry = (digit1 + digit2 + carry) / 10
          pos1 -= 1
          pos2 -= 1
      # reverse res
      return "".join(res[::-1])
  
label_desc: Use image node_id 1 for calling the Solution obj's underlying member method code with example usage: obj.addStrings(num1, num2) and returns: str