code: def test_subclassing_metric():
      class EmptyMetric(dipysmetric.Metric):
          pass
  
      metric = EmptyMetric()
      assert_raises(
          NotImplementedError, metric.are_compatible, None, None
      )
      assert_raises(NotImplementedError, metric.dist, None, None)
  
file_path: dipy/dipy/segment/tests/test_metric.py
imports: import itertools
  import numpy
  from numpy.testing import assert_array_equal, assert_raises, assert_almost_equal, assert_equal
  import dipy.segment.featurespeed
  import dipy.segment.metric
  import dipy.segment.metricspeed
  from dipy.testing import assert_true, assert_false, assert_greater_equal, assert_less_equal
  from dipy.testing.decorators import set_random_number_generator
label_desc: Use image node_id 4 for calling a global function with example usage: test_subclassing_metric() without return types