code: def square_add_simplify(expr):
      if not (expr[0] == "#CPow2.0000e+00" and expr[1][0] == "#Add"):
          return None
      terms = []
      for i in range(1, len(expr[1])):
          terms.append(("#CPow2.0000e+00", expr[1][i]))
          for j in range(i + 1, len(expr[1])):
              terms.append(("#Mul", (2.0,), expr[1][i], expr[1][j]))
      return ("#Add",) + tuple(terms)
  
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 21 for calling a global function with example usage: square_add_simplify(expr) and returns: unknown, None