code: def dtype_pipeline(np_type, placeholder_dali_type):
      res = fn.external_source(
          source=np.zeros((8, 1), dtype=np_type),
          dtype=placeholder_dali_type,
      )
  
      return res
  
imports: import numpy
  import nvidia.dali.fn
  import nvidia.dali.types
  import warnings
  from numpy.testing import assert_array_equal
  from nvidia.dali import pipeline_def
  from nvidia.dali.backend_impl import TensorCPU, TensorListCPU, TensorListGPU
  from nvidia.dali.backend_impl import types
  import nvidia.dali
  from nose_utils import assert_raises
  from nose import SkipTest
  from test_utils import dali_type_to_np, py_buffer_from_address, get_device_memory_info
label_desc: Use image node_id 26 for calling a global function with example usage: dtype_pipeline(np_type, placeholder_dali_type) and returns: res