🚀 go-pugleaf

   I have done a little bit with the boxes in TeX, but there's a lot I don't
know.  My apologies if this is an easy question:
 
   Is there a simple way to write a macro \di#1#2 which takes boxes defined by
#1 and #2 and gives a new box with lower right corner of #1 joined to upper 
left corner of #2?  If possible, I would prefer to avoid using box registers.
                                               Charles Blair