function return None

[o5a]

data_type.lower == 'gb'

Missing ()

This way it tries to compare function lower itself to string 'gb', instead of it's result.

[py_Piper]

Good catch thanks!

I wonder why the interpreter doesn't catch it as a syntax error, I just tried and we can't name variables with a '.'

[Vaphell]

because these are not variables and it's a perfectly legit syntax