code: def mul(a, b):
      """
      This is for test_pickle, since the function still has to be
      reachable from pickle (as in it cannot be defined inline)
      """
      return a * b
  
file_path: pytensor/tests/compile/test_ops.py
imports: import pickle
  import numpy
  from pytensor import function
  from pytensor.compile.ops import as_op
  from pytensor.tensor.type import dmatrix, dvector
  from tests import unittest_tools
label_desc: Use image node_id 1 for calling a global function with example usage: mul(a, b) and returns: unknown