code: public static <T> boolean noneEqualForHashable(final Iterable<T> iterable) {
      return Iterables.size(iterable) == ImmutableSet.copyOf(iterable).size();
    }
docs: Returns true if and only if no two elements of the provided {@link Iterable} are equal to one
  another.  Equality is determined by {@code .equals()}. Elements must have a {@code hashCode}
  consistent with their {@code equals} or the result is undefined.
  
  No element may be {@code null} or an exception will be thrown.