code: function tokenize(text) {
    if (text == null || text == "")
      return [];
    var tokens = [];
    var s = "";
    for (var i=0; i<text.length; i++) {
      var c = text.charAt(i);
      if (c == " ")
      {
        if (s)
          tokens.push(s);
        s = "";
      } else if (c == "." || c == "," || c == "!" || c == "?") {
        if (s)
          tokens.push(s);
        s = "";
        tokens.push(c);
      } else {
        s += c;
      }
    }
    if (s)
      tokens.push(s);
    return tokens;
  }
docs: text utility