input: Write a function to generate a Python class for an online store item that includes fields for ID, name, price, and description. The class should include an initialization method, a string representation method, and a method to convert the object to a dictionary format.
  assert StoreItem(1, 'Book', 9.99, 'A great read')
  assert str(StoreItem(2, 'T-shirt', 15.99, 'Comfortable and stylish')) == 'T-shirt, $15.99'
  assert StoreItem(3, 'Headphones', 29.99, 'High-quality sound').to_dict() == {'item_id': 3, 'name': 'Headphones', 'price': 29.99, 'description': 'High-quality sound'}
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:.2f}"
  
      def to_dict(self):
          return {
              'item_id': self.item_id,
              'name': self.name,
              'price': self.price,
              'description': self.description
          }