Abusing the short-circuit of OR to allow recursive definitions

evil_or_tree.py

from dataclasses import dataclass

@dataclass
class Empty:
    pass

@dataclass
class Tree:
    value: int
    left: Empty or Tree
    right: Empty or Tree
    
root = Tree(5, Tree(4, Tree(3, Empty(), Empty()),
                    Empty()),
            Tree(4, Empty(), Empty()))
print(root)