+class ANamedargExpr
+ super AExpr
+ var n_id: TId is writable, noinit
+ var n_assign: TAssign is writable, noinit
+ var n_expr: AExpr is writable, noinit
+end
+class ASafeExpr
+ super AExpr
+ var n_expr: AExpr is writable, noinit
+ var n_quest: TQuest is writable, noinit
+end