input: Write a function that generates a Python class for an online store item with fields for ID, name, price, and description. The class should include an __init__ method to initialize these fields, a __str__ method to return a string representation of the item, and a to_dict method to convert the item to a dictionary format.
  
  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, 'Book', 10.99, 'A great book'))=='Book, $10.99'
  assert StoreItem(1, 'Book', 10.99, 'A great book').to_dict()=={'item_id': 1, 'name': 'Book', 'price': 10.99, 'description': 'A great book'}
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
          }
  