input: Write a class representing an online store item with attributes for ID, name, price, and description. The class should include a method to convert the item to a dictionary.
  
  class StoreItem:
      def __init__(self, item_id, name, price, description):
          self.item_id = item_id
          self.name = name
          self.price = price
          self.description = description
  
      def __str__(self):
          return f'{self.name}, ${self.price}'
  
      def to_dict(self):
          return {
              'item_id': self.item_id,
              'name': self.name,
              'price': self.price,
              'description': self.description
          }
  
  assert str(StoreItem(1, "Laptop", 999.99, "High-end gaming laptop")) == "Laptop, $999.99"
  assert StoreItem(2, "Mouse", 19.99, "Wireless gaming mouse").to_dict() == {'item_id': 2, 'name': 'Mouse', 'price': 19.99, 'description': 'Wireless gaming mouse'}
output: def to_dict(self):
      return {
          'item_id': self.item_id,
          'name': self.name,
          'price': self.price,
          'description': self.description
      }