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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 find_one(self, **kwargs):
 """Returns future. Executes collection's find_one method based on keyword args maps result ( dict to instance ) and return future Example:: manager = EntityManager(Product) product_saved = yield manager.find_one(_id=object_id) """

        future = TracebackFuture()

        def handle_response(result, error):
            if error:
                future.set_exception(error)
            else:
                instance = self.__entity()
                instance.map_dict(result)
                future.set_result(instance)

        self.__collection.find_one(kwargs, callback=handle_response)

        return future