from typing import Callable, Iterator
from abc import ABC, abstractmethod

class LlmEngine(ABC):
    @abstractmethod
    def infer(self, system_prompt: str, main_context: str, continuation_text: str, should_stop: Callable[[], bool] = lambda: False) -> Iterator[str]:
        pass

    @abstractmethod
    def token_count(self, system_prompt: str, main_context: str) -> int:
        pass

    @abstractmethod
    def token_limit(self) -> int:
        pass