class_docstr: Basically a batch of active trajectories and a list of completed ones.
class_docstr_tok: ["Basically","a","batch","of","active","trajectories","and","a","list","of","completed","ones","."]
docstr: Clear the first `num` completed trajectories, or all if num is None.
code: def clear_completed_trajectories(self, num=None):
      """Clear the first `num` completed trajectories, or all if num is None."""
      if num is None:
          self._completed_trajectories = []
      else:
          self._completed_trajectories = self._completed_trajectories[
              num:
          ]
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import os
  import pickle
  import re
  import sys
  import time
  from absl import logging
  import cloudpickle
  import numpy
  from tensor2tensor.envs import time_step
  import tensorflow.compat.v1
label_desc: Use image node_id 6 for calling the BatchTrajectory obj's underlying member method code with example usage: obj.clear_completed_trajectories(num) without return types