def make_sampling_histogram(unique_words):
    """Helper function for test_stochastic_sample (below).
       Given a list of words, return a dictionary representing a histogram.
       All values begin at zero.
       Param: unique_words(list): every distinct type of word, will be a key
       Return: histogram_empty(dict)
    """
    histogram_empty = dict()
    for word in unique_words:
        histogram_empty[word] = 0
    return histogram_empty