code: public static <T extends Comparable<T>> Range<T> is(final T element) {
          return between(element, element, null);
      }
docs: <p>Obtains a range using the specified element as both the minimum
  and maximum in this range.</p>
  
  <p>The range uses the natural ordering of the elements to determine where
  values lie in the range.</p>
  
  @param <T> the type of the elements in this range
  @param element  the value to use for this range, not null
  @return the range object, not null
  @throws IllegalArgumentException if the element is null
  @throws ClassCastException if the element is not {@code Comparable}