code: def hash_key(self, s):
      # hash string with 26 length array
      table = [0] * 26
      for ch in s:
          index = ord(ch) - ord("a")
          table[index] += 1
      return str(table)
  
label_desc: Use image node_id 2 for calling the Solution obj's underlying member method code with example usage: obj.hash_key(s) and returns: str