Creation of a new Namespace. This function will refuse to
          create a namespace with a similar prefix than an existing
          one present on this node. We use href==None in the case of
           an element creation where the namespace was not defined.

def newNs(self, href, prefix):
        """Creation of a new Namespace. This function will refuse to
          create a namespace with a similar prefix than an existing
          one present on this node. We use href==None in the case of
           an element creation where the namespace was not defined. """
        ret = libxml2mod.xmlNewNs(self._o, href, prefix)
        if ret is None:raise treeError('xmlNewNs() failed')
        __tmp = xmlNs(_obj=ret)
        return __tmp