@adampalay @jzoldak this is for performance reasons.

You will waste time for `log.debug("something: %s" % x)` or `log.debug("something: {}".format(x))`, but not for `log.debug("something: %s", x)`. In the latter case, the string formatting will be handled in the method and you won't get the performance hit if it won't be logged. This is because instead of making a format string, we're passing arguments to the logging function. Then, if and only if we actually hit this line of code and log something, does the logging function perform the string substitution. Thus, logging functions should always be in this format.

Note also it's a Pylint error to do `log.debug("something: %s" % x)`.