code: def _build_instance_handler_mapping(cls, instance, handle_d):
          
          res = {}
          for member_name, sig_name in handle_d.items():
              if sig_name in res:
                  sig_handlers = res[sig_name]
              else:
                  sig_handlers = res[sig_name] = []
              sig_handlers.append(getattr(instance, member_name))
          return res
docs: For every unbound handler, get the bound version.