Fixed shebangs, added error checking

samples/python2/digits.py

@@ -1,4 +1,4 @@
-#/usr/bin/env python
+#!/usr/bin/env python
 
 '''
 SVM and KNearest digit recognition.
@@ -23,12 +23,19 @@ Usage:
    digits.py
 '''
 
-import numpy as np
-import cv2
+# built-in modules
 from multiprocessing.pool import ThreadPool
-from common import clock, mosaic
+
+import cv2
+
+import numpy as np
 from numpy.linalg import norm
 
+# local modules
+from common import clock, mosaic
+
+
+
 SZ = 20 # size of each digit is SZ x SZ
 CLASS_N = 10
 DIGITS_FN = 'data/digits.png'