def make_feature(wordlist, toplist):
    """Return a feature vector corresponding to a wordlist.
        The wordlist represents an article.
        We count the incidences in wordlist of each word in toplist.
    """
    # This could be optimized if necessary.
    feature = [wordlist.count(word) for word in toplist]
    binary_feature = [int(f>0) for f in feature] 
    # I return the binary version for now, rather than worry about
    # the proper normalization.
    return binary_feature