def namespaced(namespace, name):
    """Returns name in Clark notation within the given namespace.

       For example namespaced("source") in an XLIFF document might return::
           {urn:oasis:names:tc:xliff:document:1.1}source

       This is needed throughout lxml.
    """
    if namespace:
        return "{%s}%s" % (namespace, name)
    else:
        return name