如何在spyne中指定带有in的请求参数？

import spyne

class MyService(spyne.Service):
    @spyne.srpc(Unicode, _in='body')
    def my_method(self, request):
        # 处理请求
        return "Response"

application = spyne.Application([MyService], 'my_namespace')

if __name__ == '__main__':
    from wsgiref.simple_server import make_server
    server = make_server('localhost', 8000, application)
    server.serve_forever()