Documented [get].

doc/main.tex

@@ -2536,6 +2536,18 @@ is done via \verb+i+ successive invocations of \verb+pop+. Thus,
 \verb+pop_many 1+ is \verb+pop+. The index \verb+i+ must be nonnegative. The
 time complexity is $O(i)$.
 
+%% val get
+
+\begin{verbatim}
+  val get: int -> 'a env -> element option
+\end{verbatim}
+
+\verb+get i env+ returns the parser's \verb+i+-th stack element. The index
+\verb+i+ is 0-based: thus, \verb+get 0+ is \verb+top+. If \verb+i+ is greater
+than or equal to the number of elements in the stack, \verb+None+ is returned.
+\verb+get+ is implemented using \verb+pop_many+ and \verb+top+: its time
+complexity is $O(i)$.
+
 %% val positions
 
 \begin{verbatim}

src/IncrementalEngine.ml

@@ -275,7 +275,7 @@ module type INCREMENTAL_ENGINE = sig
 
   val pop_many: int -> 'a env -> 'a env option
 
-  (* [get i env] returns the parser's [i]-th stack cell. The index [i] is
+  (* [get i env] returns the parser's [i]-th stack element. The index [i] is
      0-based: thus, [get 0] is [top]. If [i] is greater than or equal to the
      number of elements in the stack, [None] is returned. The time complexity
      is O(i). *)