[BioC] GO categories: how to extract a specific rank of the category-tree

[Johannes Graumann]

Hi all,

Can anyone point me into the direction on how to achieve the subject line? 
I'm using right now the "CustomEndNodeList" from "goTools", retrieve two
consecutive ranks and accept only what I retrieve with the higher rank and
not with the lower ... but GO has rank-skipping connections and I would
prefer to really be able to slice the tree at level x below ID y while
disregarding those ...

Thanks for any pointers, Joh