## attribute_old_value property


Set to true if attributes is true or omitted and target’s attribute value before the mutation needs to be recorded.
### Definition:
```python
@property
def attribute_old_value(self):
    ...
@attribute_old_value.setter
def attribute_old_value(self, value):
    ...
```

### See Also
* module [`aspose.html.dom.mutations`](../../)
* class [`MutationObserverInit`](/html/python-net/aspose.html.dom.mutations/mutationobserverinit)