docs: def log_to_file(filename, level=DEBUG):
      """send paramiko logs to a logfile, if they're not already going somewhere"""
      l = logging.getLogger("paramiko")
      if len(l.handlers) > 0:
          return
      l.setLevel(level)
      f = open(filename, 'w')
      lh = logging.StreamHandler(f)
      lh.setFormatter(logging.Formatter('%(levelname)-.3s [%(asctime)s.%(msecs)03d] thr=%(_threadid)-3d %(name)s: %(message)s',
                                        '%Y%m%d-%H:%M:%S'))
      l.addHandler(lh)