[swig-python] fix examples after e0c07d

KeySet.__getitem__ throws KeyError if key is missing
(see https://docs.python.org/3/reference/datamodel.html#object.__getitem__)

This fixes #1

src/bindings/swig/python/examples/example_kdb.py

@@ -7,11 +7,13 @@
 	db.get(ks, "user/MyApp")
 
 	# check if key exists
-	key = ks.lookup("user/MyApp/mykey")
-	if not key:
+	try:
+		key = ks["user/MyApp/mykey"]
+	except KeyError:
 		# create a new key + append to keyset
 		key = kdb.Key("user/MyApp/mykey")
 		ks.append(key)
+
 	# change keys value
 	key.value = "new_value"
 

src/bindings/swig/python/examples/example_keyset.py

@@ -29,7 +29,11 @@
 print("  KeySet1[1]={0}".format(ks1[1]))
 print("  KeySet1[-1]={0}".format(ks1[-1]))
 print("  KeySet1['user/key1']={0}".format(ks1["user/key1"]))
-print("  KeySet1['doesnt_exist']={0}".format(ks1["doesnt_exist"]))
+try:
+	print("  KeySet1['doesnt_exist']={0}".format(ks1["doesnt_exist"]))
+except KeyError:
+	print("  KeySet1['doesnt_exist'] throws KeyError")
+print("  KeySet1.lookup('doesnt_exist')={0}".format(ks1.lookup("doesnt_exist")))
 print("")
 
 print("You asked for slices? You get slices:")