input: Write a python function to count the number of items in the database.
  assert count_items() == 0  # Initially no items
  item = Item(name='Test Item')
  item.save()
  assert count_items() == 1  # After adding one item
  item2 = Item(name='Test Item 2')
  item2.save()
  assert count_items() == 2  # After adding another item
  item.delete()
  assert count_items() == 1  # After deleting one item
output: def count_items():
      return Item.objects.count()