code: def placeholder(dim=None):
      return tf.placeholder(
          dtype=tf.float32, shape=combined_shape(None, dim)
      )
  
file_path: spinningup/spinup/algos/tf1/vpg/core.py
imports: import numpy
  import tensorflow
  import scipy.signal
  from gym.spaces import Box, Discrete
label_desc: Use image node_id 2 for calling a global function with example usage: placeholder(dim) and returns: tf