added _doc.py -- doc-string ckecking utility

added some sample description

samples/python2/_coverage.py

@@ -1,24 +1,29 @@
+'''
+Utility for measuring python opencv API coverage by samples.
+'''
+
 from glob import glob
 import cv2
 import re
 
-cv2_callable = set(['cv2.'+name for name in dir(cv2) if callable( getattr(cv2, name) )])
+if __name__ == '__main__':
+    cv2_callable = set(['cv2.'+name for name in dir(cv2) if callable( getattr(cv2, name) )])
 
-found = set()
-for fn in glob('*.py'):
-    print ' --- ', fn
-    code = open(fn).read()
-    found |= set(re.findall('cv2?\.\w+', code))
+    found = set()
+    for fn in glob('*.py'):
+        print ' --- ', fn
+        code = open(fn).read()
+        found |= set(re.findall('cv2?\.\w+', code))
 
-cv2_used = found & cv2_callable
-cv2_unused = cv2_callable - cv2_used
-with open('unused_api.txt', 'w') as f:
-    f.write('\n'.join(sorted(cv2_unused)))
+    cv2_used = found & cv2_callable
+    cv2_unused = cv2_callable - cv2_used
+    with open('unused_api.txt', 'w') as f:
+        f.write('\n'.join(sorted(cv2_unused)))
 
-r = 1.0 * len(cv2_used) / len(cv2_callable)
-print '\ncv2 api coverage: %d / %d  (%.1f%%)' % ( len(cv2_used), len(cv2_callable), r*100 )
+    r = 1.0 * len(cv2_used) / len(cv2_callable)
+    print '\ncv2 api coverage: %d / %d  (%.1f%%)' % ( len(cv2_used), len(cv2_callable), r*100 )
 
-print '\nold (cv) symbols:'
-for s in found:
-    if s.startswith('cv.'):
-        print s
+    print '\nold (cv) symbols:'
+    for s in found:
+        if s.startswith('cv.'):
+            print s