Add a new node to @parent, at the end of the child (or
          property) list merging adjacent TEXT nodes (in which case
          @cur is freed) If the new node is ATTRIBUTE, it is added
          into properties instead of children. If there is an
           attribute with equal name, it is first destroyed.

def addChild(self, cur):
        """Add a new node to @parent, at the end of the child (or
          property) list merging adjacent TEXT nodes (in which case
          @cur is freed) If the new node is ATTRIBUTE, it is added
          into properties instead of children. If there is an
           attribute with equal name, it is first destroyed. """
        if cur is None: cur__o = None
        else: cur__o = cur._o
        ret = libxml2mod.xmlAddChild(self._o, cur__o)
        if ret is None:raise treeError('xmlAddChild() failed')
        __tmp = xmlNode(_obj=ret)
        return __tmp