code: def reconstruct_expr(expr):
      if is_number(expr[0]):
          return expr[0]
      if expr[0] == "#x":
          raise ValueError(
              "#x cannot appear in expr to be reconstructed."
          )
      args = [reconstruct_expr(i) for i in expr[1:]]
      if str(expr[0])[:5] == "#CPow":
          return tf.pow(args[0], np.float32(expr[0][5:]))
      if expr[0][0] == "#":
          tf_fn = _extractable_nodes.get(expr[0][1:], None)
          assert tf_fn is not None
          return tf_fn(*args)
      assert False
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import numpy
  import tensorflow
label_desc: Use image node_id 4 for calling a global function with example usage: reconstruct_expr(expr) and returns: expr, tf, tf_fn