code: def searchNs(self, doc, nameSpace):
          
          if doc is None: doc__o = None
          else: doc__o = doc._o
          ret = libxml2mod.xmlSearchNs(doc__o, self._o, nameSpace)
          if ret is None:raise treeError('xmlSearchNs() failed')
          __tmp = xmlNs(_obj=ret)
          return __tmp
docs: Search a Ns registered under a given name space for a
            document. recurse on the parents until it finds the defined
            namespace or return None otherwise. @nameSpace can be None,
            this is a search for the default namespace. We don't allow
            to cross entities boundaries. If you don't declare the
            namespace within those you will be in troubles !!! A
             warning is generated to cover this case.