class_docstr: trpo class
class_docstr_tok: ["trpo","class"]
docstr: flat concat input
  :param xs: a list of tensor
  :return: flat tensor
docstr_tok: ["flat","concat","input",":","param","xs",":","a","list","of","tensor",":","return",":","flat","tensor"]
code: def _flat_concat(self, xs):
      """
      flat concat input
      :param xs: a list of tensor
      :return: flat tensor
      """
      return tf.concat([tf.reshape(x, (-1,)) for x in xs], axis=0)
  
imports: import argparse
  import copy
  import os
  import threading
  import time
  import gym
  import matplotlib.pyplot
  import numpy
  import scipy.signal
  import tensorflow
  import tensorflow_probability
  import tensorlayer
label_desc: Use image node_id 7 for calling the TRPO obj's underlying member method code with example usage: obj._flat_concat(xs) and returns: tf