tweak to fig 7.4

book.tex

@@ -3790,7 +3790,7 @@ addq |$\Arg_1$|, |$\itm{var}$|
 \end{lstlisting}
 \end{transformation}
 %
-On the other hand, if $\Atm_1$ is not the same variable as the
+On the other hand, if $\Atm_2$ is not the same variable as the
 left-hand side, then we can move $\Arg_1$ into the left-hand \itm{var}
 and then add $\Arg_2$ to \itm{var}.
 %
@@ -12536,7 +12536,7 @@ class TypeCheckLtup(TypeCheckLwhile):
           case TupleType(ts):
             return ts[i]
           case _:
-            raise Exception('error: expected a tuple, not ' + repr(tup_ty))
+            raise Exception('expected a tuple, not ' + repr(tup_ty))
       case _:
         return super().type_check_exp(e, env)
 \end{lstlisting}