code: def testAdditiveTypeRaises2(self):
      with pm.Model() as model:
          cov_func = pm.gp.cov.ExpQuad(3, [0.1, 0.2, 0.3])
          gp1 = pm.gp.Latent(cov_func=cov_func)
          gp2 = pm.gp.Marginal(cov_func=cov_func)
          with pytest.raises(Exception) as e_info:
              gp1 + gp2
  
imports: from functools import reduce
  from operator import add
  import numpy
  import numpy.testing
  import pytest
  import pymc
  from pymc.math import cartesian
label_desc: Use image node_id 7 for calling the TestGPAdditive obj's underlying member method code with example usage: obj.testAdditiveTypeRaises2() without return types