input: Write a function to create a Python class for an online store item that includes fields for ID, name, price, and description. The class should have an initialization method to set these fields and a method to convert the object to a dictionary representation.
  
  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, "High-end gaming laptop")) == "Laptop, $999"
  assert StoreItem(2, "Mouse", 20, "Wireless mouse").to_dict() == {'item_id': 2, 'name': 'Mouse', 'price': 20, 'description': 'Wireless mouse'}
  assert str(StoreItem(3, "Keyboard", 50, "Mechanical keyboard")) == "Keyboard, $50"
  assert StoreItem(4, "Monitor", 200, "27-inch 4K monitor").to_dict() == {'item_id': 4, 'name': 'Monitor', 'price': 200, 'description': '27-inch 4K monitor'}
output: 
  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
          }
  