code: def _update_possible_actions_mask(self) -> None:
      # pyre-fixme[16]: `PossibleActionsMaskTester` has no attribute `legal_action`.
      self.legal_action = np.random.randint(self.action_num)
      # pyre-fixme[16]: `PossibleActionsMaskTester` has no attribute
      #  `possible_actions_mask`.
      self.possible_actions_mask = np.zeros(self.action_num, dtype=bool)
      self.possible_actions_mask[self.legal_action] = True
  
file_path: ReAgent/reagent/gym/envs/functionality/possible_actions_mask_tester.py
imports: import gym
  import numpy
  from gym.spaces import Box, Discrete
label_desc: Use image node_id 2 for calling the PossibleActionsMaskTester obj's underlying member method code with example usage: obj._update_possible_actions_mask() without return types