code: public static <T> Predicate<T> not(Predicate<T> predicate) {
          dbc.precondition(predicate != null, "cannot negate a null predicate");
          return predicate.negate();
      }
docs: Negates the given predicate.
  
  @param <T> the element type parameter
  @param predicate the predicate to be negated
  @return the negated predicate