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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 restart(state, host, ctid, force=False):
    '''
    Restart OpenVZ containers.

    + ctid: CTID of the container to restart
    + force: whether to force container start
    '''

    yield stop(state, host, ctid)
    yield start(state, host, ctid, force=force)