code: def test_forest_trivial():
      """test creation of forest object"""
      F = Forest(5)
      assert F.E == 0
      assert (F.cc() == np.arange(5)).all()
  
file_path: nipy/nipy/algorithms/graph/tests/test_forest.py
imports: import numpy
  from ..forest import Forest
label_desc: Use image node_id 3 for calling a global function with example usage: test_forest_trivial() without return types