def METHOD_NAME(self):
    """
    Retrieve all QuestionGraph data, cache it.
    """
    # Retrieve all relevant edges, questions and answers
    self._edges = self._get_edges(self._q_graph)
    self._nx_graph = self._build_nx_graph(self._q_graph, self._edges)
    self._questions = self._get_all_questions(self._nx_graph)
    # setup caches for quick access
    self._edges_by_id = {e.id: e for e in self._edges}
    self._questions_by_id = {q.id: q for q in self._questions}
    self._reachable_questions_by_id = self._get_reachable_questions(self._nx_graph, self._q_graph)
    self._endpoint_questions_by_id = self._get_endpoint_questions(
        self._nx_graph, self._questions_by_id, self._reachable_questions_by_id)