[chimera-dev] changing position for a residue using python

Hi all, I have a problem with a prot and it seems that renumbering could help. I'd like to automatically add 230 to the residue number of the aa of my second chain. As I feared, when looping other residue to change res.id.position, my script fails as position can not be modified. How could I do this? Should I delete position and re-create it? Best JD