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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 rbd_exists(service, pool, rbd_img):
 """Check to see if a RADOS block device exists."""

    try:
        out = check_output(['rbd', 'list', '--id',
                            service, '--pool', pool])
        if six.PY3:
            out = out.decode('UTF-8')
    except CalledProcessError:
        return False

    return rbd_img in out