def opt_jobs(self, number):
        """
        Number of local workers to run, a strictly positive integer.
        """
        try:
            number = int(number)
        except ValueError:
            raise usage.UsageError(
                "Expecting integer argument to jobs, got '%s'" % number)
        if number <= 0:
            raise usage.UsageError(
                "Argument to jobs must be a strictly positive integer")
        self["jobs"] = number

        Number of local workers to run, a strictly positive integer.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/scripts/trial.py