import abc

# For 2 and 3 compatibility
# https://stackoverflow.com/questions/35673474/
ABC = abc.ABCMeta('ABC', (object,), {'__slots__': ()})


class BaseOfficeFile(ABC):
    def __init__(self):
        pass

    @abc.abstractmethod
    def load_key(self):
        pass

    @abc.abstractmethod
    def decrypt(self):
        pass

import abc

# For 2 and 3 compatibility
# https://stackoverflow.com/questions/35673474/
ABC = abc.ABCMeta('ABC', (object,), {'__slots__': ()})


class BaseOfficeFile(ABC):
    def __init__(self):
        pass

    @abc.abstractmethod
    def load_key(self):
        pass

    @abc.abstractmethod
    def decrypt(self):
        pass

    @abc.abstractmethod
    def is_encrypted(self):
        pass

Add is_encrypted() to abstract methods
Add is_encrypted() to abstract methods
