def _procFDImplementation(self):
        """
        Simple implementation for systems where /proc/pid/fd exists (we assume
        it works).
        """
        dname = "/proc/%d/fd" % (self.getpid(),)
        return [int(fd) for fd in self.listdir(dname)]

        Simple implementation for systems where /proc/pid/fd exists (we assume
        it works).
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/process.py