def append(self, file: File) -> None:
        """Add file to the Files collection."""
        if file.src_uri in self._src_uris:
            warnings.warn(
                "To replace an existing file, call `remove` before `append`.", DeprecationWarning
            )
            del self._src_uris[file.src_uri]
        self._src_uris[file.src_uri] = file
Add file to the Files collection.
mkdocs/structure/files.py