code: def test_tree_space_best_tree():
      new_tree_space = tree.TreeSpace(1, 1, 0, 1)
  
      assert isinstance(new_tree_space.best_tree, node.Node)
  
imports: from opytimizer.core import node
  from opytimizer.spaces import tree
label_desc: Use image node_id 13 for calling a global function with example usage: test_tree_space_best_tree() without return types