Return log message containing ellapsed time as a string.

        When true, do_reset will result in a reset of start time.

def result(self, msg, do_reset=False):
        """Return log message containing ellapsed time as a string.

        When true, do_reset will result in a reset of start time.

        """
        result = "%s (%s s)" % (msg, time.time() - self.start)
        if do_reset:
            self.start = time.time()
        return result