input: Write a function to implement a hash table in Python that supports insert, delete, and retrieve operations. If the given key is not found during the retrieve operation, return None.
  assert hash_table.insert("key1", 23) == None
  assert hash_table.retrieve("key1") == 23
  assert hash_table.delete("key1") == None
  assert hash_table.retrieve("key1") == None
output: def __init__(self):
      self.table = {}
  
  def insert(self, key, value):
      self.table[key] = value
  
  def retrieve(self, key):
      return self.table.get(key, None)
  
  def delete(self, key):
      if key in self.table:
          del self.table[key]