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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 can_fetch(self, request: Request, file=None) -> bool:
        '''Return whether the request can fetched.

        Args:
            request: Request.
            file: A file object to where the robots.txt contents are written.

        Coroutine.
        '''
        try:
            return self.can_fetch_pool(request)
        except NotInPoolError:
            pass

        yield from self.fetch_robots_txt(request, file=file)

        return self.can_fetch_pool(request)