input: Write a python function to determine if a product has expired based on its expiry date and calculate the number of days left before the product expires.
  ```python
  assert ProductExpiry(1, datetime(2023, 10, 15)).is_expired() == False
  assert ProductExpiry(1, datetime(2022, 5, 1)).is_expired() == True
  assert ProductExpiry(1, datetime(2023, 10, 15)).get_time_left() > 0
  assert ProductExpiry(1, datetime(2022, 5, 1)).get_time_left() < 0
output: from datetime import datetime, timedelta
  
  class ProductExpiry:
      def __init__(self, product_id, expiry_date):
          self.product_id = product_id
          self.expiry_date = expiry_date
  
      def is_expired(self):
          return datetime.now() > self.expiry_date
  
      def get_time_left(self):
          delta = self.expiry_date - datetime.now()
          return delta.days