code: def callback_python(a, user_data=None):
      if a == ERROR_VALUE:
          raise ValueError("bad value")
  
      if user_data is None:
          return a + 1
      else:
          return a + user_data
  
file_path: scipy/scipy/_lib/tests/test_ccallback.py
imports: from numpy.testing import assert_equal, assert_
  from pytest import raises
  import time
  import pytest
  import ctypes
  import threading
  from scipy._lib import _ccallback_c
  from scipy._lib import _test_ccallback
  from scipy._lib._ccallback import LowLevelCallable
label_desc: Use image node_id 1 for calling a global function with example usage: callback_python(a, user_data) and returns: unknown, unknown