code: def test_multitrace_nonunique(self):
      with pytest.raises(ValueError):
          base.MultiTrace([self.strace0, self.strace1])
  
imports: import numpy
  import numpy.testing
  import pytest
  from pymc.backends import base, ndarray
  from tests.backends import fixtures
label_desc: Use image node_id 2 for calling the TestMultiTrace obj's underlying member method code with example usage: obj.test_multitrace_nonunique() without return types