docs: def _list_machines(self):
          """
          Request a list of all added machines.
  
          Populates self._machines dict with mist.client.model.Machine instances
          """
          try:
              req = self.request(self.mist_client.uri+'/clouds/'+self.id+'/machines')
              machines = req.get().json()
          except:
              # Eg invalid cloud credentials
              machines = {}
  
          if machines:
              for machine in machines:
                  self._machines[machine['machine_id']] = Machine(machine, self)
          else:
              self._machines = {}