docstr: Test __repr__ method.
docstr_tok: ["Test","__repr__","method","."]
code: def test_repr(self):
      """Test __repr__ method."""
      policy = DTypePolicy("mixed_float16")
      self.assertEqual(repr(policy), '<DTypePolicy "mixed_float16">')
  
imports: from keras.mixed_precision import DTypePolicy
  from keras.mixed_precision import dtype_policy
  from keras.mixed_precision import set_dtype_policy
  from keras.testing import test_case
label_desc: Use image node_id 8 for calling the DTypePolicyTest obj's underlying member method code with example usage: obj.test_repr() without return types