code: def _parent_changed(self, parent):
          
          from .index_operations import ParameterIndexOperationsView
          #if getattr(self, "_in_init_"):
              #import ipdb;ipdb.set_trace()
              #self.constraints.update(param.constraints, start)
              #self.priors.update(param.priors, start)
          offset = parent._offset_for(self)
          for name, iop in list(self._index_operations.items()):
              self.remove_index_operation(name)
              self.add_index_operation(name, ParameterIndexOperationsView(parent._index_operations[name], offset, self.size))
          self._fixes_ = None
          for p in self.parameters:
              p._parent_changed(parent)
docs: From Parentable:
          Called when the parent changed
  
          update the constraints and priors view, so that
          constraining is automized for the parent.