def deepcopy(self, scope=None):
_ = scope
mother = self.get_mother().deepcopy()
children = [x.deepcopy() for x in self.get_children()]
copy = Rule(mother, children)
Scope.deepcopy(self, copy)
# I haven't thought through whether the next lines are necessary.
# They don't hurt.
copy.get_mother().set_scope(copy)
for child in copy.get_children():
child.set_scope(copy)
return copy
