[cctbxbb] cluster coordinates to asymmetric unit

Hi, I'm trying to work out how to cluster atomic coordinates into one asymmetric unit in a crystal for a given spacegroup rather than the atomic coordinates placed in arbitrary asymmetric unit copies in the unit cell. I think the tools to be used must be in cctbx.crystal.direct_space_asu and I have been trying but failed to understand how the test tst_crystal_asu_clusters.py works. Is there already a phenix or cctbx program that can do this? Many thanks, Robert