docs: public Choice<T> condition(final Predicate<? super T> predicate) {
      checkNotNull(predicate);
      final Choice<T> thisChoice = this;
      return new Choice<T>() {
        @Override
        protected Iterator<T> iterator() {
          return Iterators.filter(thisChoice.iterator(), predicate);
        }
  
        @Override
        public String toString() {
          return String.format("%s.condition(%s)", thisChoice, predicate);
        }
      };
    }