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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def master_for(self, service_name, redis_class=StrictRedis, connection_pool_class=SentinelConnectionPool, **kwargs):
 """ Returns a redis client instance for the ``service_name`` master. A SentinelConnectionPool class is used to retrive the master's address before establishing a new connection. NOTE: If the master's address has changed, any cached connections to the old master are closed. By default clients will be a redis.StrictRedis instance. Specify a different class to the ``redis_class`` argument if you desire something different. The ``connection_pool_class`` specifies the connection pool to use. The SentinelConnectionPool will be used by default. All other keyword arguments are merged with any connection_kwargs passed to this class and passed to the connection pool as keyword arguments to be used to initialize Redis connections. """

        kwargs['is_master'] = True
        connection_kwargs = dict(self.connection_kwargs)
        connection_kwargs.update(kwargs)
        return redis_class(connection_pool=connection_pool_class(
            service_name, self, **connection_kwargs))