Incoming<RoutingPolicy>&
 Incoming<RoutingPolicy>::operator>> (T& t) throw(NoSuchPartError)
 {
   check_has_part(cur_extract_idx_);
   get(*(parts_[cur_extract_idx_++]), t, binary_mode_);
   return *this;
 }
 const Part&
 Multipart::operator[](size_t i) const throw (NoSuchPartError)
 {
   check_has_part(i);
   return (*parts_ptr_)[i];
 }