code: def fromfd(cls, fd, signals):
          
          if fd < 0:
              _err_closed()
          self = cls.__new__()
          object.__init__(self)
          self._sfd = fd
          self._signals = signals
          return self
docs: Create a new signalfd object from a given file descriptor
  
          :param fd:
              A pre-made file descriptor obtained from ``signalfd_create(2)`
          :param signals:
              A pre-made frozenset that describes the monitored signals
          :raises ValueError:
              If fd is not a valid file descriptor
          :returns:
              A new signalfd object
  
          .. note::
              If the passed descriptor is incorrect then various methods will
              fail and raise OSError with an appropriate message.