code: def substr(request):
      return request.param
  
imports: import numba
  import numpy
  import pandas
  import pytest
  from numba import cuda
  from numba.core.typing import signature
  from numba.types import CPointer, void
  import rmm
  import cudf
  from cudf._lib.strings_udf import column_from_udf_string_array, column_to_string_view_array
  from cudf.core.udf.strings_typing import str_view_arg_handler, string_view, udf_string
  from cudf.core.udf.utils import _PTX_FILE, _get_extensionty_size
  from cudf.testing._utils import assert_eq, sv_to_udf_str
  from cudf.utils._numba import _CUDFNumbaConfig
label_desc: Use image node_id 5 for calling a global function with example usage: substr(request) and returns: request