Traversal function for the "preceding-sibling" direction
          The preceding-sibling axis contains the preceding siblings
          of the context node in reverse document order; the first
          preceding sibling is first on the axis; the sibling
           preceding that node is the second on the axis and so on.

def xpathNextPrecedingSibling(self, ctxt):
        """Traversal function for the "preceding-sibling" direction
          The preceding-sibling axis contains the preceding siblings
          of the context node in reverse document order; the first
          preceding sibling is first on the axis; the sibling
           preceding that node is the second on the axis and so on. """
        if ctxt is None: ctxt__o = None
        else: ctxt__o = ctxt._o
        ret = libxml2mod.xmlXPathNextPrecedingSibling(ctxt__o, self._o)
        if ret is None:raise xpathError('xmlXPathNextPrecedingSibling() failed')
        __tmp = xmlNode(_obj=ret)
        return __tmp