st: Graph bar problem

["moleps islon" <moleps2@gmail.com>]

Dear statalisters,
I need to create a bar graph containing 2 different summed
variables(X,Y) sorted by category (Z). However I also need the X,Y
variables to be stacked by variable P.  I've tried graph bar (sum) x
y, over(P) asyvars stack over(Z) and different variations over this
theme but none of them seem to work. Any ideas?
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