Merge pull request #1440 from rocreguant/master

bugfix: 'last_iteration' not initialized

Author: CamDavidsonPilon

lifelines/fitters/aalen_additive_fitter.py

@@ -223,6 +223,7 @@ def _fit_model_to_data_batch(self, X, T, E, weights, show_progress):
         variance_hazards_ = np.zeros((n_deaths, d))
         v = np.zeros(d)
         start = time.time()
+        last_iteration = 0
 
         W = np.sqrt(weights)
         X = W[:, None] * X