function URLify(s, num_chars) {

    // changes, e.g., "Petty theft" to "petty_theft"

    // remove all these words from the string before urlifying

    removelist = ["a", "an", "as", "at", "before", "but", "by", "for", "from",

                  "is", "in", "into", "like", "of", "off", "on", "onto", "per",

                  "since", "than", "the", "this", "that", "to", "up", "via",

                  "with"];

    r = new RegExp('\\b(' + removelist.join('|') + ')\\b', 'gi');

    s = s.replace(r, '');

    s = s.replace(/[^-A-Z0-9\s]/gi, '');  // remove unneeded chars

    s = s.replace(/^\s+|\s+$/g, ''); // trim leading/trailing spaces

    s = s.replace(/[-\s]+/g, '-');   // convert spaces to hyphens

    s = s.toLowerCase();             // convert to lowercase

    return s.substring(0, num_chars);// trim to first num_chars chars

}