code: def test_default_dtype_instance(self, dtype_char):
      if dtype_char in "SU":
          dtype = np.dtype(dtype_char + "1")
      elif dtype_char == "V":
          # Legacy behaviour was to use V8. The reason was float64 being the
          # default dtype and that having 8 bytes.
          dtype = np.dtype("V8")
      else:
          dtype = np.dtype(dtype_char)
  
      discovered_dtype, _ = ncu._discover_array_parameters(
          [], type(dtype)
      )
  
      assert discovered_dtype == dtype
      assert discovered_dtype.itemsize == dtype.itemsize
  
imports: from itertools import permutations, product
  import pytest
  from pytest import param
  import numpy
  import numpy._core._multiarray_umath
  from numpy._core._rational_tests import rational
  from numpy.testing import assert_array_equal, assert_warns, IS_PYPY
label_desc: Use image node_id 10 for calling the TestScalarDiscovery obj's underlying member method code with example usage: obj.test_default_dtype_instance(dtype_char) without return types