def refitPrefixes(self):
        """
        Refit namespace qualification by replacing prefixes
        with explicit namespaces. Also purges prefix mapping table.
        @return: self
        @rtype: L{Element}
        """
        for c in self.children:
            c.refitPrefixes()
        if self.prefix is not None:
            ns = self.resolvePrefix(self.prefix)
            if ns[1] is not None:
                self.expns = ns[1]
        self.prefix = None
        self.nsprefixes = {}
        return self
Refit namespace qualification by replacing prefixes
        with explicit namespaces. Also purges prefix mapping table.
        @return: self
        @rtype: L{Element}