code: public <T extends Enum<T>> Optional<T> answer(final Class<T> enumClass) {
          return fromNullable(askBuilder.answer(enumClass));
      }
docs: Return user input as Optional<T extends Enum<T>>. Complete with enum values.
  
  @param enumClass Class of enum to return
  @param <T> the return type
  @return user input as enum value