code: def _setup(self):
      space_2 = GraphSpace(2)
      metric = space_2.metric
      metric.set_aligner(ExhaustiveAligner())
  
      metrics = [metric] * 2
  
      estimators = [_AACFrechetMean(metric) for metric in metrics]
      estimators[0].init_point = gs.zeros((2, 2))
  
      self.data_generators = [
          _TrivialMeanData(metrics, estimators, n_reps=2)
      ]
      self.basic_data_generators = [_TrivialData(_AACFrechetMean)]
  
imports: import geomstats.backend
  from geomstats.geometry.stratified.graph_space import ExhaustiveAligner, GraphSpace, _GeodesicToPointAligner
  from geomstats.learning.aac import _AACGGPCA, _AACFrechetMean, _AACRegression
  from geomstats.test.data import TestData
  from geomstats.test.test_case import np_backend
label_desc: Use image node_id 1 for calling the AACFrechetMeanTestData obj's underlying member method code with example usage: obj._setup() without return types