Represent object hierarchy in the related model with django-mptt

Question

I have two models, see below. How can I represent page attribute as a tree in my CardWidget form? I.e. I want it to be rendered the same way as it happens in my Page form, it should be a properly indented tree.

models.py

class Page(MPTTModel):
    parent = TreeForeignKey('self', null=True, blank=True, related_name='children', on_delete=models.SET_NULL)


class CardWidget(models.Model):
    title = models.CharField(max_length=100)
    page = models.ForeignKey(Page, blank=True, null=True)