text: from abc import ABC, abstractmethod
  
  
  class Order:
      pass
  
  
  class ShippingStrategy(ABC):
      @abstractmethod
      def calculate(self, order):
          pass
  
  
  class FedExStrategy(ShippingStrategy):
      def calculate(self, order):
          return 3.0
  
  
  class UPSStrategy(ShippingStrategy):
      def calculate(self, order):
          return 4.0
  
  
  class PostalStrategy(ShippingStrategy):
      def calculate(self, order):
          return 5.0
  
  
  class ShippingCost:
      def __init__(self, strategy):
          self.strategy = strategy
  
      def calculate(self, order):
          return self.strategy.calculate(order)
  