def machine(self, machine_id, credentials=False):
        """
        ::
        
            GET /:login/machines/:id
        
        :param machine_id: unique identifier for a machine to be found in the 
            datacenter
        :type machine_id: :py:class:`basestring`
        
        :rtype: :py:class:`smartdc.machine.Machine`
        """
        if isinstance(machine_id, dict):
            machine_id = machine_id['id']
        elif isinstance(machine_id, Machine):
            machine_id = machine_id.id
        return Machine(datacenter=self, machine_id=machine_id, 
                credentials=credentials)