docs: def processRequest(cls, ps, **kw):
          """invokes callback that should return a (request,response) tuple.
          representing the SOAP request and response respectively.
          ps -- ParsedSoap instance representing HTTP Body.
          request -- twisted.web.server.Request
          """
          resource = kw['resource']
          method = resource.getOperation(ps, None) # This getOperation method is valid for ServiceSOAPBinding subclass
          rsp = method(ps, **kw)[1] # return (request, response) but we only need response
          return rsp