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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 load_fd(self, key, noexpire=False):
        '''Look up an item in the cache and return an open file
        descriptor for the object.  It is the caller's responsibility
        to close the file descriptor.'''

        cachekey = self.xform_key(key)
        path = self.path(cachekey)

        try:
            stat = path.stat()
            if not noexpire and stat.st_mtime < time.time() - self.lifetime:
                LOG.debug('%s has expired', key)
                path.unlink()
                raise KeyError(key)

            LOG.debug('%s found in cache', key)
            return path.open('rb')
        except OSError:
            LOG.debug('%s not found in cache', key)
            raise KeyError(key)