TAAE2 example in documentation / MIX2 missing ?

Bergerac · December 2016

If I get it right, MIX2 is missing here:

renderer.block = ^(const AERenderContext * _Nonnull context) {
 AEModuleProcess(file1, context); // Run player (pushes 1)
 AEModuleProcess(filter1, context); // Run filter (edits top buffer)
 AEModuleProcess(file2, context); // Run player (pushes 1)
 AEModuleProcess(file3, context); // Run player (pushes 1)
 AEBufferStackMix(context->stack, 2); // Mix top 2 buffers
 AEModuleProcess(filter2, context); // Run filter (edits top buffer)
 AERenderContextOutput(context, 1); // Put top buffer onto output
 AEModuleProcess(recorder, context); // Run recorder (uses top buffer)
};