keras/src/saving/saving_lib.py/NpzIOStore/close
class NpzIOStore:    def close(self):
        if self.mode == "w":
            if self.archive:
                self.f = self.archive.open(
                    self.root_path, mode="w", force_zip64=True
                )
            else:
                self.f = open(self.root_path, mode="wb")
            np.savez(self.f, **self.contents)
        self.f.close()