code: def test_display(self):
      board = deepchem.rl.envs.tictactoe.TicTacToeEnvironment()
      s = board.display()
      assert s.find("X") == -1
  
file_path: deepchem/deepchem/rl/envs/test_tictactoe.py
imports: from unittest import TestCase
  import numpy
  import deepchem.rl.envs.tictactoe
label_desc: Use image node_id 5 for calling the TestTicTacToeEnvironment obj's underlying member method code with example usage: obj.test_display() without return types