/usr/lib/python3/dist-packages/invoke/vendor/lexicon/attribute_dict.py is in python3-invoke 0.11.1+dfsg1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13  | class AttributeDict(dict):
    def __getattr__(self, key):
        try:
            return self[key]
        except KeyError:
            # to conform with __getattr__ spec
            raise AttributeError(key)
    def __setattr__(self, key, value):
        self[key] = value
    def __delattr__(self, key):
        del self[key]
 |