code: def checkValidString(self, s):
      lo = hi = 0
      for c in s:
          lo += 1 if c == "(" else -1
          hi += 1 if c != ")" else -1
          if hi < 0:
              break
          lo = max(lo, 0)
  
      return lo == 0
  
label_desc: Use image node_id 1 for calling the Solution obj's underlying member method code with example usage: obj.checkValidString(s) and returns: unknown