def app_context_processor(
        self, f: T_template_context_processor
    ) -> T_template_context_processor:
        """Like :meth:`context_processor`, but for templates rendered by every view, not
        only by the blueprint. Equivalent to :meth:`.Flask.context_processor`.
        """
        self.record_once(
            lambda s: s.app.template_context_processors.setdefault(None, []).append(f)
        )
        return f
Like :meth:`context_processor`, but for templates rendered by every view, not
        only by the blueprint. Equivalent to :meth:`.Flask.context_processor`.
        
src/flask/sansio/blueprints.py