message: fixed flatMapValues
diff: @@ -130,17 +130,19 @@ namespace iroha {
  }
  template <typename C, typename T, typename F>
  - auto flatMapValues(T &t, F &&f) {
  - return t | [&](auto &st) -> boost::optional<C> {
  - return boost::copy_range<C>(
  - st | boost::adaptors::transformed([&](auto &t) {
  - return apply(t, std::forward<F>(f));
  - })
  - | boost::adaptors::filtered(
  - [](auto &r) { return static_cast<bool>(r); })
  - | boost::adaptors::transformed([](auto &&r) { return *r; }));
  + boost::optional<C> flatMapValues(T &t, F &&f) {
  + if (t) {
  + C map_result;
  + for (auto &inp_el : *t) {
  + apply(inp_el, std::forward<F>(f)) |
  + [&map_result](auto &&transformed_el) {
  + map_result.emplace_back(std::move(transformed_el));
  };
  }
  + return map_result;
  + }
  + return boost::none;
  + }
  template <typename R, typename T, typename F>
  auto flatMapValue(T &t, F &&f) {
  