input: Write a function to implement the Strategy Pattern with the given classes and methods.
  assert s1.execute() == "Hello world!"
  assert s2.execute() == "Hola mundo!"
  assert s3.execute() == "Mere saath kaam kar!"
output: class Context:
      def __init__(self, strategy):
          self._strategy = strategy
  
      def execute(self):
          return self._strategy.execute()
  
  class Strategy:
      def execute(self):
          pass
  
  class StrategyEnglish(Strategy):
      def execute(self):
          return "Hello world!"
  
  class StrategySpanish(Strategy):
      def execute(self):
          return "Hola mundo!"
  
  class StrategyHindi(Strategy):
      def execute(self):
          return "Mere saath kaam kar!"
  
  s1 = Context(StrategyEnglish())
  s2 = Context(StrategySpanish())
  s3 = Context(StrategyHindi())