code: def test_element_of_rejects_unhashable_type(self, dtype_):
      class C(Classifier):
          dtype = dtype_
          missing_value = dtype.type("1")
          inputs = ()
          window_length = 0
  
      c = C()
  
      with self.assertRaises(TypeError) as e:
          c.element_of([{"a": 1}])
  
      errmsg = str(e.exception)
      expected = (
          "Expected `choices` to be an iterable of hashable values,"
          " but got [{'a': 1}] instead.\n"
          "This caused the following error: "
          "TypeError(\"unhashable type: 'dict'\",)."
      )
      self.assertEqual(errmsg, expected)
  
imports: from functools import reduce
  import operator
  import numpy
  import pandas
  from zipline.lib.labelarray import LabelArray
  from zipline.pipeline import Classifier
  from zipline.pipeline.data.testing import TestingDataSet
  from zipline.pipeline.expression import methods_to_ops
  from zipline.testing import parameter_space
  from zipline.testing.fixtures import ZiplineTestCase
  from zipline.testing.predicates import assert_equal
  from zipline.utils.numpy_utils import categorical_dtype, int64_dtype
  from .base import BaseUSEquityPipelineTestCase
label_desc: Use image node_id 12 for calling the ClassifierTestCase obj's underlying member method code with example usage: obj.test_element_of_rejects_unhashable_type(dtype_) without return types