\code{.cpp}
io_context ios;
-child c("ls", on_exit=[](int exit, const std::error_code& ec_in){});
+child c("ls", ios, on_exit=[](int exit, const std::error_code& ec_in){});
std::future<int> exit_code;
-chlid c2("ls", on_exit=exit_code);
+chlid c2("ls", ios, on_exit=exit_code);
\endcode