Create root-node hash
Current level is zero
Establish limits: max & min nodes per level, number of levels
root{A0} = add_levels($current_level, $level_limit, $min_nodes, $max_nodes);

sub add_levels {
    return if current level is > the limit, bump it if not
    calculate a random number between high and low limit
    new_level = {};
    for $n (0..$local_limit) {
      generate $name from level and $n
      new_level{$name} = add_levels($current_level, $limit, $min, $max)
    }
    return $new_level;
}