code: def init_app(self, app: Flask) -> None:
      self._get_feature_flags_func = app.config[
          "GET_FEATURE_FLAGS_FUNC"
      ]
      self._is_feature_enabled_func = app.config[
          "IS_FEATURE_ENABLED_FUNC"
      ]
      self._feature_flags = app.config["DEFAULT_FEATURE_FLAGS"]
      self._feature_flags.update(app.config["FEATURE_FLAGS"])
  
imports: from copy import deepcopy
  from flask import Flask
label_desc: Use image node_id 2 for calling the FeatureFlagManager obj's underlying member method code with example usage: obj.init_app(app) without return types