Interfaces [python-ABC] - Typescript to Python field guide

interfaces.py

from abc import ABC, abstractmethod


class FileHandlerABC(ABC):
    @abstractmethod
    def open(self) -> bytes:
        ...

    @abstractmethod
    def close(self) -> None:
        ...

# with usage like: 

def get_contents(file_handler: FileHandlerABC) -> bytes:
    assert isinstance(file_handler, FileHandlerABC)
    try:
        return file_handler.open()
    finally:
        file_handler.close()

# note this must extend the abstract base class
class MyFile(FileHandlerABC):
    def open(self) -> bytes:
        return b"hello"

    def close(self) -> None:
        return

contents = get_contents(MyFile()) # b"hello"