code: def test_invalid_dtype_size(self):
      with self.assertRaises(ValueError):
          dtype_utils.dtype_size("unknown_dtype")
  
imports: from keras.backend.common.keras_tensor import KerasTensor
  from keras.testing import test_case
  from keras.utils import dtype_utils
label_desc: Use image node_id 9 for calling the DtypeSizeTests obj's underlying member method code with example usage: obj.test_invalid_dtype_size() without return types