from typing import Protocol, List

class Template(Protocol):
    name: str        # This is a protocol member
    value: int = 0   # This one too (with default)

    def method(self) -> None:
        self.temp: List[int] = [] # Error in type checker

class Concrete:
    def __init__(self, name: str, value: int) -> None:
        self.name = name
        self.value = value

    def method(self) -> None:
        return

var: Template = Concrete('value', 42)  # OK