input: from typing import Any
  
  
  class HashTable:
      def __init__(self):
          self.table = [[] for _ in range(256)]
  
      def insert(self, key: Any, value: Any):
          h = hash(key) % 256
          for i, kv in enumerate(self.table[h]):
              if kv[0] == key:
                  self.table[h][i] = (key, value)
                  return
          self.table[h].append((key, value))
  
      def retrieve(self, key: Any) -> Any:
          h = hash(key) % 256
          for kv in self.table[h]:
              if kv[0] == key:
                  return kv[1]
  
      def delete(self, key: Any):
          h = hash(key) % 256
          for i, kv in enumerate(self.table[h]):
              if kv[0] == key:
                  del self.table[h][i]
  
  
  # Test cases
  ht = HashTable()
  ht.insert("key1", "value1")
  ht.insert("key2", "value2")
  print(ht.retrieve("key1"))  # Output: value1
  ht.delete("key1")
  print(ht.retrieve("key1"))  # Output: None
output:     def __contains__(self, key: Any) -> bool:
          h = hash(key) % 256
          for kv in self.table[h]:
              if kv[0] == key:
                  return True
          return False
  
      def __len__(self) -> int:
          count = 0
          for bucket in self.table:
              count += len(bucket)
          return count
  
      def keys(self) -> List[Any]:
          key_list = []
          for bucket in self.table:
              for kv in bucket:
                  key_list.append(kv[0])
          return key_list
  
      def values(self) -> List[Any]:
          value_list = []
          for bucket in self.table:
              for kv in bucket:
                  value_list.append(kv[1])
          return value_list
  
      def items(self) -> List[Tuple[Any, Any]]:
          item_list = []
          for bucket in self.table:
              for kv in bucket:
                  item_list.append(kv)
          return item_list
  
  # Additional test cases
  ht.insert("key3", "value3")
  print("key3" in ht)  # Output: True
  print(len(ht))  # Output: 2
  print(ht.keys())  # Output: ['key2', 'key3']
  print(ht.values())  # Output: ['value2', 'value3']
  print(ht.items())  # Output: [('key2', 'value2'), ('key3', 'value3')]