grault_frobnicator.py

from dataclasses import dataclass
from typing import Literal, Protocol, Optional


class Side:
    ...


class Wombat:
    ...


class Frobnicator(Protocol):
    def frobnicate(self, left: Optional[Wombat], right: Optional[Wombat]):
        ...


@dataclass
class Fnord:
    is_triangular: bool


@dataclass
class Grault:
    color: Literal["red", "green"]
    fnord: Fnord
    left: Optional[Wombat]
    right: Optional[Wombat]


class GraultFrobnicator:
    def __init__(self, frobnicator: Frobnicator):
        self.frobnicator = frobnicator

    def frobnicate(self, grault: Grault):
        if not (
            (grault.color is None)
            or (grault.color == "red" and grault.fnord.is_triangular)
        ):
            return

        if grault.left is None and grault.right is None:
            return

        self.frobnicator.frobnicate(grault.left, grault.right)