docs: def daemonize(self):
          """Double-fork magic"""
          if self.userid:
              uid = pwd.getpwnam(self.userid).pw_uid
              os.seteuid(uid)
          try:
              pid = os.fork()
              if pid > 0:
                  sys.exit(0)
          except OSError as err:
              sys.stderr.write("First fork failed: {0} ({1})\n".format(err.errno, err.strerror))
              sys.exit(1)
          # decouple from parent environment
          os.chdir("/")
          os.setsid()
          os.umask(0)
  
          # Second fork
  
          try:
              pid = os.fork()
              if pid > 0:
                  sys.exit(0)
          except OSError as err:
              sys.stderr.write("Second fork failed: {0} ({1})\n".format(err.errno, err.strerror))
              sys.exit(1)
  
          sys.stdout.flush()
          sys.stderr.flush()
          si = open(self.stdin, 'r')
          so = open(self.stdout, 'w')
          se = open(self.stderr, 'w')
          os.dup2(si.fileno(), sys.stdin.fileno())
          os.dup2(so.fileno(), sys.stdout.fileno())
          os.dup2(se.fileno(), sys.stderr.fileno())
  
          # write PID file
          atexit.register(self.delpid)
          pid = str(os.getpid())
          open(self.pidfile, 'w').write("%s\n" % pid)