.py

from abc import abstractmethod
from typing import Generic, Protocol, TypeVar

T_cov = TypeVar("T", contravariant=True)
U_cov = TypeVar("U", contravariant=True)

class Metric(Protocol[T]):
    @abstractmethod
    def __call__(self, gt: T, pred: T) -> float:
        ...

class SomeMetric(Metric[int]):
    def __call__(self, gt: int, pred: int) -> float:
        return 0

class MetricsStructure(Generic[T_cov]):
    m1: T_cov
    m2: T_cov


class MetricCollection(Protocol[U_cov]):
    def __init__(self, metrics: MetricsStructure[Metric[U]]):
        self.__metrics = metrics

    def __call__(self, gt: U_cov, pred: U_cov) -> MetricsStructure[float]:
        return {}