code: def readFd(fd, URL, encoding, options):
      
      ret = libxml2mod.xmlReadFd(fd, URL, encoding, options)
      if ret is None:raise treeError('xmlReadFd() failed')
      return xmlDoc(_obj=ret)
docs: parse an XML from a file descriptor and build a tree. NOTE
        that the file descriptor will not be closed when the reader
         is closed or reset.