python __all__ = __ALL__ = []

Question

__all__ = __ALL__ = classes

这句代码，我知道__all__是为了限制别的代码引用，但是中间加个__ALL__又是什么意思？

import pkgutil
from .base import BaseCrawler
import inspect


# load classes subclass of BaseCrawler
classes = []
for loader, name, is_pkg in pkgutil.walk_packages(__path__):
    module = loader.find_module(name).load_module(name)
    for name, value in inspect.getmembers(module):
        globals()[name] = value
        if inspect.isclass(value) and issubclass(value, BaseCrawler) and value is not BaseCrawler \
                and not getattr(value, 'ignore', False):
            classes.append(value)
__all__ = __ALL__ = classes

Answer 1

应该没有实际意义，加不加__ALL__都一样