code: def add_const_simplify(expr):
      """Prunes branches not containing any #x nodes."""
      if expr[0] != "#Add":
          return None
      did_something = False
      new_args = []
      for i in range(1, len(expr)):
          if expr_contains(expr[i], "#x"):
              new_args.append(expr[i])
          else:
              did_something = True
      if did_something:
          return ("#Add",) + tuple(new_args)
  
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 23 for calling a global function with example usage: add_const_simplify(expr) and returns: None, unknown