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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def readerForFd(fd, URL, encoding, options):
 """Create an xmltextReader for an XML from a file descriptor. The parsing flags @options are a combination of xmlParserOption. NOTE that the file descriptor will not be closed when the reader is closed or reset. """

    ret = libxml2mod.xmlReaderForFd(fd, URL, encoding, options)
    if ret is None:raise treeError('xmlReaderForFd() failed')
    return xmlTextReader(_obj=ret)