docs: def link_for_image(self, base_dir: str, conf: Config) -> int:
          """Link all artifacts required for a Docker image under `base_dir` and
             return the number of linked artifacts."""
          return self.link_types(
              base_dir,
              [ArtifactType.app, ArtifactType.binary, ArtifactType.gen_py],
              conf)