Why not also mention string formatting? Not all string concatenation is for creating new strings. Often when working with strings, your end goal is providing some output to the end user.

a = 'Hello'
b = 'World'
logger.info(’{}, {}’.format(a, b))

Or newer syntax:

logger.info(f’{a}, {b}’)

PS, I was not able to make proper single quotes on this mobile keyboard