def test_beginLoggingToDontRedirect(self):
        """
        L{LogBeginner.beginLoggingTo} will leave the existing stdout/stderr in
        place if it has been told not to replace them.
        """
        oldOut = self.sysModule.stdout
        oldErr = self.sysModule.stderr
        self.beginner.beginLoggingTo((), redirectStandardIO=False)
        self.assertIs(self.sysModule.stdout, oldOut)
        self.assertIs(self.sysModule.stderr, oldErr)

        L{LogBeginner.beginLoggingTo} will leave the existing stdout/stderr in
        place if it has been told not to replace them.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/logger/test/test_global.py