def resolvePrefix(self, prefix):
        """
        Resolve the specified prefix to a known namespace.
        @param prefix: A declared prefix
        @type prefix: basestring
        @return: The namespace that has been mapped to I{prefix}
        @rtype: (I{prefix}, I{name})
        """
        ns = Namespace.default
        if self.parent is not None:
            ns = self.parent.resolvePrefix(prefix)
        return ns