\begin{camlexample}{toplevel}
\begin{caml}
\begin{camlinput}
$\?$ [@@@warning "+A"];;
\end{camlinput}
\end{caml}
\begin{caml}
\begin{camlinput}
$\?$ 1 + <<2.>> ;;
\end{camlinput}
\begin{camlerror}
Error: The constant 2. has type float but an expression was expected of type
         int
\end{camlerror}
\end{caml}
\begin{caml}
\begin{camlinput}
$\?$ let f <<x>> = () ;;
\end{camlinput}
\begin{camlwarn}
Warning 27 [unused-var-strict]: unused variable x.

val f : 'a -> unit = <fun>
\end{camlwarn}
\end{caml}
\end{camlexample}

\begin{camlexample}{toplevel}
\begin{caml}
\begin{camlinput}
$\?$ Format.printf "Hello@.";
  print_endline "world";;
\end{camlinput}
\begin{camloutput}
Hello
world
- : unit = ()
\end{camloutput}
\end{caml}
\end{camlexample}