Use operand record in TAC expression visitor

Rakefile

@@ -38,11 +38,20 @@ desc 'Convert previous stage language into the current stage language'
 task :convert do
   File.open('boot/stage20/cl.elna', 'w') do |current_stage|
     File.readlines('boot/stage19/cl.elna').each do |line|
-      if line.include? "_assign_at(@classification, 1, ElnaLexerClass.eof)"
-        current_stage << "\tclassification[1] := ElnaLexerClass.eof;\n"
-      else
-        current_stage << line
-      end
+      current_stage << line
     end
+    current_stage << <<~FUN
+
+      proc f(m: ElnaInstructionModule);
+      begin
+      end;
+
+      proc g();
+      var
+      	x: ElnaInstructionModule;
+      begin
+      	f(x)
+      end;
+    FUN
   end
 end