std::transform(begin(*execs), end(*execs), rexecs.get(),
[](const ExecPtr& exec) { return static_cast<kernel::activity::ExecImpl*>(exec->pimpl_.get()); });
std::transform(begin(*execs), end(*execs), rexecs.get(),
[](const ExecPtr& exec) { return static_cast<kernel::activity::ExecImpl*>(exec->pimpl_.get()); });