+def nb_missing_properties(descr, height, width):
+ if type(descr) == list:
+ return [ nb_missing_properties(d, height, width) for d in descr ]
+
+ d = descr.split('<img>', 1)
+ if len(d) == 0: return 0
+ d = d[0].strip().split('<sep>')
+ d = [ x.strip() for x in d ]
+
+ requested_properties = set(d)
+ all_properties = set(descr2properties(descr, height, width))
+ missing_properties = requested_properties - all_properties
+
+ return (len(requested_properties), len(all_properties), len(missing_properties))
+
+######################################################################
+