@Blind4Basics: The "concatenation devil" was implied in unpythonic :)

That'd depend on the particular implementation, actually. e.g JS V8 engine (aka what Node uses) actually implements strings as kind of a string builder, so concatenating strings has string builder like performance for free.

And what about the string concatenation devil? x) (that's a bigger problem than the unpythonic aspect, imo)

This looks like some crappy Java code ;-)

Also there are some unnessary operations, and things that you should never do ;-)

This is not a best practice. Glueing strings this way is un-pythonic.