code: def test_add(self):
      X = np.linspace(0, 1, 10)[:, None]
      with pm.Model() as model:
          mean1 = pm.gp.mean.Linear(coeffs=2, intercept=0.5)
          mean2 = pm.gp.mean.Constant(2)
          mean = mean1 + mean2 + mean2
      M = mean(X).eval()
      npt.assert_allclose(M[1], 0.7222 + 2 + 2, atol=1e-3)
  
file_path: pymc/tests/gp/test_mean.py
imports: import numpy
  import numpy.testing
  import pymc
label_desc: Use image node_id 1 for calling the TestAddProdMean obj's underlying member method code with example usage: obj.test_add() without return types