code: public static void checkForNonNegativeElements(IntTuple t)
      {
          for (int i=0; i<t.getSize(); i++)
          {
              if (t.get(i) < 0)
              {
                  throw new IllegalArgumentException("Negative size: "+t);
              }
          }
      }
docs: Checks whether the elements of the given tuple are not negative,
  and throws an <code>IllegalArgumentException</code> if any of
  them is negative.
  
  @param t The tuple
  @throws NullPointerException If the given size is <code>null</code>
  @throws IllegalArgumentException If any element of the given tuple
  is negative