def add_etag(self, overwrite=False, weak=False):
        if overwrite or 'etag' not in self.headers:
            self.set_etag(generate_etag(self.get_data()), weak)
Add an etag for the current response if there is none yet.
dataset/ETHPy150Open Eforcers/gae-flask-todo/lib/werkzeug/wrappers.py/ETagResponseMixin.add_etag