deepcopy_with_paths

Copy only the containers along the given paths.

Used to guard against mutation by extract_files without copying the entire structure. Only dicts and lists that lie on a path are copied; everything else is returned by reference.

For example, given paths=[["foo", "files", "file"]] and the structure: { "foo": { "bar": {"baz": {}}, "files": {"file": } } } The root dict, "foo", and "files" are copied (they lie on the path). "bar" and "baz" are returned by reference (off the path).