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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 engine(func):
 """Callback-oriented decorator for asynchronous generators. This is an older interface; for new code that does not need to be compatible with versions of Tornado older than 3.0 the `coroutine` decorator is recommended instead. This decorator is similar to `coroutine`, except it does not return a `.Future` and the ``callback`` argument is not treated specially. In most cases, functions decorated with `engine` should take a ``callback`` argument and invoke it with their result when they are finished. One notable exception is the `~tornado.web.RequestHandler` :ref:`HTTP verb methods <verbs>`, which use ``self.finish()`` in place of a callback argument. """

    func = _make_coroutine_wrapper(func, replace_callback=False)

    @functools.wraps(func)
    def wrapper(*args, **kwargs):
        future = func(*args, **kwargs)

        def final_callback(future):
            if future.result() is not None:
                raise ReturnValueIgnoredError(
                    "@gen.engine functions cannot return values: %r" %
                    (future.result(),))
        # The engine interface doesn't give us any way to return
        # errors but to raise them into the stack context.
        # Save the stack context here to use when the Future has resolved.
        future.add_done_callback(stack_context.wrap(final_callback))
    return wrapper