hash the data bytes to be compatible with python 3

Python 3's hash() function only accepts specific kinds of data, so converting the numpy array to bytes in order to hash it

Author: yossiz74

notebooks/tensorflow/Tensorflow-1-NotMNIST.ipynb

@@ -878,9 +878,9 @@
     "valid_dataset.flags.writeable = False\n",
     "test_dataset.flags.writeable = False\n",
     "\n",
-    "train_hash = [hash(e.data) for e in train_dataset]\n",
-    "valid_hash = [hash(e.data) for e in valid_dataset]\n",
-    "test_hash = [hash(e.data) for e in test_dataset]\n",
+    "train_hash = [hash(e.tobytes()) for e in train_dataset]\n",
+    "valid_hash = [hash(e.tobytes()) for e in valid_dataset]\n",
+    "test_hash = [hash(e.tobytes()) for e in test_dataset]\n",
     "\n",
     "unique_train_hash = set(train_hash)\n",
     "valid_overlap = unique_train_hash.intersection(set(valid_hash))\n",