'Build a URL to query the proxy resolver.
@param xri: An XRI to resolve.
@type xri: unicode
@param service_type: The service type to resolve, if you desire
service endpoint selection.  A service type is a URI.
@type service_type: str
@returns: a URL
@returntype: str'

def queryURL(self, xri, service_type=None):

    qxri = toURINormal(xri)[6:]
    hxri = (self.proxy_url + qxri)
    args = {'_xrd_r': 'application/xrds+xml'}
    if service_type:
        args['_xrd_t'] = service_type
    else:
        args['_xrd_r'] += ';sep=false'
    query = _appendArgs(hxri, args)
    return query
