code: def test_fit():
      """[Parallel | Learner] Testing fit flags"""
      lr = Learner(OLS(), indexer=data.indexer, name="lr")
      assert not lr.__fitted__
      _run(lr, "fit", X, y)
      assert lr.__fitted__
  
imports: import numpy
  from mlens.testing import Data, EstimatorContainer
  from mlens.parallel import Group, Learner, Pipeline, run
  from mlens.utils.dummy import OLS, Scale
  from mlens.externals.sklearn.base import clone
label_desc: Use image node_id 2 for calling a global function with example usage: test_fit() without return types