simple type as __in_header__ does not work

server.py

import logging
from spyne.model.primitive import Boolean, Unicode, Integer
from spyne.model.complex import ComplexModel
from spyne.service import ServiceBase
from spyne.decorator import rpc


class SomeService(ServiceBase):
    __in_header__ = Unicode(sub_name='myinfo')

    @rpc(Unicode)
    def MyMethod(ctx, mymethodparam):
        print "I got:", mymethodparam
        print "myinfo:", ctx.in_header


if __name__ == '__main__':
    from spyne.application import Application
    from spyne.protocol.soap import Soap11
    from spyne.server.wsgi import WsgiApplication
    from wsgiref.simple_server import make_server

    logging.basicConfig(level=logging.DEBUG)
    logging.info('listening to http://127.0.0.1:8000')

    application = Application([SomeService],
                          'myapp',
                          in_protocol=Soap11(validator='lxml'),
                          out_protocol=Soap11())

    wsgi_application = WsgiApplication(application)
    server = make_server('127.0.0.1', 8000, wsgi_application)
    server.serve_forever()