When a user program a new lattice/model and provides a checkerboard decomposition, it would useful to have an automatic check of the validity of the checkerboard decomposition. I have a routine for that, which tests: - Check that the memory allocation of ```List_Fam```: the second size should be *at least* the maximum size of the families. - Check for bond duplication in the family lists - Check that every bond is present only once in the family lists - Check that indeed every pair of families commute