We have absolute control over the final stereo-isomer that comes out of the synthesis.  The large molecules are assembled from building blocks that each contain two stereo centers. We synthesize all four stereo-isomers of the building blocks in separate bottles and then put them together in different sequences to create the large molecules.
Where the programming (Clasp Common Lisp in the molecular design language that I&#x27;ll announce soon) comes in is we can build computer models of all stere-isomers and, in software, figure out which ones can do the job that we want. Then we just synthesize that and test it in the lab.