I spend a lot of time to replace gammu with python-gsmmodem for my Huawei E3531.
The python exemple is just an exemple, it's incomplete. It does not read sms in the memory (if you receive a sms before starting the script). And it does not concat multiple parts sms (it will print unordered parts).
Also, as your live read sms script is running, you cannot send sms with another script because the dongle is busy.
Here is my own script to read all kind of SMS and send in same time.