code: def addNextSibling(self, elem):
          
          if elem is None: elem__o = None
          else: elem__o = elem._o
          ret = libxml2mod.xmlAddNextSibling(self._o, elem__o)
          if ret is None:raise treeError('xmlAddNextSibling() failed')
          __tmp = xmlNode(_obj=ret)
          return __tmp
docs: Add a new node @elem as the next sibling of @cur If the new
            node was already inserted in a document it is first
            unlinked from its existing context. As a result of text
            merging @elem may be 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.