code: def _startDriver(self):
          
          framework = addict.Dict()
          framework.user = getpass.getuser() # We must determine the user name ourselves with pymesos
          framework.name = "toil"
          framework.principal = framework.name
          # Make the driver which implements most of the scheduler logic and calls back to us for the user-defined parts.
          # Make sure it will call us with nice namespace-y addicts
          self.driver = MesosSchedulerDriver(self, framework,
                                             self._resolveAddress(self.mesosMasterAddress),
                                             use_addict=True, implicit_acknowledgements=True)
          self.driver.start()
docs: The Mesos driver thread which handles the scheduler's communication with the Mesos master