'Set the signature parameter to the result of sign.'

def sign_request(self, signature_method, consumer, token):

    if ('oauth_consumer_key' not in self):
        self['oauth_consumer_key'] = consumer.key
    if (token and ('oauth_token' not in self)):
        self['oauth_token'] = token.key
    self['oauth_signature_method'] = signature_method.name
    self['oauth_signature'] = signature_method.sign(self, consumer, token)
