Method communicate

cpp-subprocess/subprocess.hpp:1440–1445

  { return stream_.send(msg); }

  std::pair<OutBuffer, ErrBuffer> communicate(const char* msg, size_t length)
  {
    auto res = stream_.communicate(msg, length);
    retcode_ = wait();
    return res;
  }

  std::pair<OutBuffer, ErrBuffer> communicate(const std::string& msg)
  {