Drop Python2 support.

samples/python/squares.py

@@ -6,14 +6,6 @@ Simple "Square Detector" program.
 Loads several images sequentially and tries to find squares in each image.
 '''
 
-# Python 2/3 compatibility
-from __future__ import print_function
-import sys
-PY3 = sys.version_info[0] == 3
-
-if PY3:
-    xrange = range
-
 import numpy as np
 import cv2 as cv
 
@@ -26,7 +18,7 @@ def find_squares(img):
     img = cv.GaussianBlur(img, (5, 5), 0)
     squares = []
     for gray in cv.split(img):
-        for thrs in xrange(0, 255, 26):
+        for thrs in range(0, 255, 26):
             if thrs == 0:
                 bin = cv.Canny(gray, 0, 50, apertureSize=5)
                 bin = cv.dilate(bin, None)
@@ -38,7 +30,7 @@ def find_squares(img):
                 cnt = cv.approxPolyDP(cnt, 0.02*cnt_len, True)
                 if len(cnt) == 4 and cv.contourArea(cnt) > 1000 and cv.isContourConvex(cnt):
                     cnt = cnt.reshape(-1, 2)
-                    max_cos = np.max([angle_cos( cnt[i], cnt[(i+1) % 4], cnt[(i+2) % 4] ) for i in xrange(4)])
+                    max_cos = np.max([angle_cos( cnt[i], cnt[(i+1) % 4], cnt[(i+2) % 4] ) for i in range(4)])
                     if max_cos < 0.1:
                         squares.append(cnt)
     return squares