input: from typing import Any
  
  class HashTable:
      def __init__(self):
          self.table = [[] for _ in range(256)]
   
      def insert(self, key: Any, value: Any) -> None:
          """ Insert a key-value pair into the hash table. If the key already exists, update its value.
          >>> ht = HashTable()
          >>> ht.insert('a', 1)
          >>> ht.retrieve('a')
          1
          >>> ht.insert('a', 2)
          >>> ht.retrieve('a')
          2
          """
          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:
          """ Retrieve the value associated with the given key.
          >>> ht = HashTable()
          >>> ht.insert('b', 3)
          >>> ht.retrieve('b')
          3
          >>> ht.retrieve('c')
          """
          h = hash(key) % 256
          for kv in self.table[h]:
              if kv[0] == key:
                  return kv[1]
   
      def delete(self, key: Any) -> None:
          """ Delete the key-value pair from the hash table.
          >>> ht = HashTable()
          >>> ht.insert('c', 4)
          >>> ht.delete('c')
          >>> ht.retrieve('c')
          """
          h = hash(key) % 256
          for i, kv in enumerate(self.table[h]):
              if kv[0] == key:
                  del self.table[h][i]
output:         return