code: def make_session(config=None, num_cpu=None, make_default=False, graph=None):
      
      if num_cpu is None:
          num_cpu = int(os.getenv('RCALL_NUM_CPU', multiprocessing.cpu_count()))
      if config is None:
          config = tf.ConfigProto(
              allow_soft_placement=True,
              inter_op_parallelism_threads=num_cpu,
              intra_op_parallelism_threads=num_cpu)
          config.gpu_options.allow_growth = True
  
      if make_default:
          return tf.InteractiveSession(config=config, graph=graph)
      else:
          return tf.Session(config=config, graph=graph)
docs: Returns a session that will use <num_cpu> CPU's only