> I've wanted something like that in Python at different times... thanks!

Python's auto-vivification doens't allow Perl's hap hazard auto-vivification. Perl allows you to say:

    my $foo = {};
    $foo->{'blah'}[0]->{'bar'}++;

And after this statement, $foo will refer a hash which has the structure as accessed in the statement.

I don't think this can be done for a generalized case in Python. Whether I want is a totally different question.