docstr: Test that vague ndpointer return values do not promote to arrays 
docstr_tok: ["Test","that","vague","ndpointer","return","values","do","not","promote","to","arrays"]
code: def test_vague_return_value(self):
      """Test that vague ndpointer return values do not promote to arrays"""
      arr = np.zeros((2, 3))
      ptr_type = ndpointer(dtype=arr.dtype)
  
      c_forward_pointer.restype = ptr_type
      c_forward_pointer.argtypes = (ptr_type,)
  
      ret = c_forward_pointer(arr)
      assert_(isinstance(ret, ptr_type))
  
imports: import sys
  import sysconfig
  import weakref
  from pathlib import Path
  import pytest
  import numpy
  from numpy.ctypeslib import ndpointer, load_library, as_array
  from numpy.testing import assert_, assert_array_equal, assert_raises, assert_equal
label_desc: Use image node_id 3 for calling the TestNdpointerCFunc obj's underlying member method code with example usage: obj.test_vague_return_value() without return types