In geany, if you click build then execute. By default, this executes your program in python2. I have by chance found a way to do either python 2 or 3.
I think you should still use
at the top of your code, as it then makes it clear to others and the normal python interpreter what to use.
You can create a new command under build to execute under python3
You can see I have added under execute command py3 execute then added an explicit command for python3.
Note for pi users : if your program uses the gpio you need to run programs in python as root with
sudo python prog.py
where prog.py is your program name
You should be able to do the same in geany by adding sudo to the execute box so it reads
sudo python “%f”
Hope this helps, as always you can e-mail or tweet me, offers of paid work at Torbay schools welcome.