docs: def _imm_setattr(self, name, value):
      '''
      A persistent immutable's setattr simply does not allow attributes to be set.
      '''
      if _imm_is_persist(self):
          raise TypeError('Attempt to change parameter \'%s\' of non-transient immutable' % name)
      elif _imm_is_trans(self):
          return _imm_trans_setattr(self, name, value)
      else:
          return _imm_init_setattr(self, name, value)