Graphical Class Hierarchy Node0 pool::RefCounter Node1 pool::IOODatabase Node0->Node1 Node2 pool::RootOODb Node1->Node2 Node3 pool::RootOOKey Node2->Node3 Node4 pool::RootOORNTuple Node2->Node4 Node5 pool::RootOOTree Node2->Node5 Node6 pool::RootOOTreeIndex Node2->Node6