def count_smoothing(freq_dist, vocabulary, alpha=1):
    """Implement simple count-based probability smoothing.
    Given a target vocabulary and a set of observed count frequencies,
    calculate a new set of counts so that Count(x) > 0 for all words
    in the target vocabulary.  This is achieved by adding `alpha`
    to each observed count
    """
    return {w: freq_dist.get(w, 0) + alpha for w in vocabulary}