'Request server to obtain a api token. Obtained
token will be set for future usage of the client instance
:return:'

def auth(self):

    auth_url = (self.api_template_url % T411API_AUTH_PATH)
    response = self.web_session.post(auth_url, self.credentials)
    json_response = response.json()
    error_description = json_response.get(u'error', None)
    if error_description:
        log.error(u'%d    -    %s', json_response.get(u'code'), error_description)
    else:
        self.set_api_token(json_response.get(u'token'))
