backcompat.py 文件源码

def upgrade_backslashreplace():
    if codecs.lookup_error('backslashreplace') is not codecs.backslashreplace_errors:
        return  # don't upgrade if someone else already has
    codecs.register_error('old-backslashreplace', codecs.backslashreplace_errors)
    codecs.register_error('backslashreplace', backslashreplace_errors)