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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 constant(value, delay=None):
 """ Returns a coroutine function that when called, always returns the provided value. This function has an alias: `paco.identity`. Arguments: value (mixed):
 value to constantly return when coroutine is called. delay (int/float):
 optional return value delay in seconds. Returns: coroutinefunction Usage:: coro = paco.constant('foo') await coro() # => 'foo' await coro() # => 'foo' """

    @asyncio.coroutine
    def coro():
        if delay:
            yield from asyncio.sleep(delay)
        return value

    return coro