It's not the same when you support slicing. foo[x:y][z] is not the same as foo[x:y,z]. I'm not sure anyone is proposing slicing to be supported with the index

It's not the same when you support slicing. foo[x:y][z] is not the same as foo[x:y,z]. I'm not sure anyone is proposing slicing to be supported with the indexing operator in C++, though, so it might not matter.