diff --git a/GMF.py b/GMF.py
index 8471310..c0f4ba3 100644
--- a/GMF.py
+++ b/GMF.py
@@ -91,7 +91,7 @@ def get_train_instances(train, num_negatives):
         # negative instances
         for t in xrange(num_negatives):
             j = np.random.randint(num_items)
-            while train.has_key((u, j)):
+            while (u, j) in train:
                 j = np.random.randint(num_items)
             user_input.append(u)
             item_input.append(j)
@@ -168,4 +168,4 @@ def get_train_instances(train, num_negatives):
 
     print("End. Best Iteration %d:  HR = %.4f, NDCG = %.4f. " %(best_iter, best_hr, best_ndcg))
     if args.out > 0:
-        print("The best GMF model is saved to %s" %(model_out_file))
\ No newline at end of file
+        print("The best GMF model is saved to %s" %(model_out_file))
diff --git a/MLP.py b/MLP.py
index 70566c7..d578826 100644
--- a/MLP.py
+++ b/MLP.py
@@ -99,7 +99,7 @@ def get_train_instances(train, num_negatives):
         # negative instances
         for t in xrange(num_negatives):
             j = np.random.randint(num_items)
-            while train.has_key((u, j)):
+            while (u, j) in train:
                 j = np.random.randint(num_items)
             user_input.append(u)
             item_input.append(j)
diff --git a/NeuMF.py b/NeuMF.py
index be04d53..d3e5b58 100644
--- a/NeuMF.py
+++ b/NeuMF.py
@@ -143,7 +143,7 @@ def get_train_instances(train, num_negatives):
         # negative instances
         for t in xrange(num_negatives):
             j = np.random.randint(num_items)
-            while train.has_key((u, j)):
+            while (u, j) in train:
                 j = np.random.randint(num_items)
             user_input.append(u)
             item_input.append(j)