code: public static <T extends Number> T mode(Collection<T> values) {
          if (values.isEmpty())
              throw new IllegalArgumentException(
                  "No mode in an empty collection");
          Counter<T> c = new ObjectCounter<T>();
          for (T n : values)
              c.count(n);
          return c.max();
      }
docs: Returns the mode value of the collection of numbers