def send_background_request(self, server_name, version, instance,
                              background_request_id):
    raise NotImplementedError()
Performs MCMC 
dataset/ETHPy150Open AppScale/appscale/AppServer/google/appengine/api/request_info.py/Dispatcher.send_background_request--crossover with--dataset/ETHPy150Open RJT1990/pyflux/pyflux/tsm.py/TSM.mcmc_fit