code: def simple_forest():
      """generate a simple forest"""
      parents = np.array([2, 2, 4, 4, 4])
      F = Forest(5, parents)
      return F
  
file_path: nipy/nipy/algorithms/graph/tests/test_forest.py
imports: import numpy
  from ..forest import Forest
label_desc: Use image node_id 1 for calling a global function with example usage: simple_forest() and returns: F