'Determine whether the node\'s resources are currently used.
Determines whether the node\'s resources should be considered used
or not. A node is used when it is either in the process of putting
a new instance on the node, has an instance on the node, or is in
the process of cleaning up from a deleted instance. Returns True if
used.
If we report resources as consumed for a node that does not have an
instance on it, the resource tracker will notice there\'s no instances
consuming resources and try to correct us. So only nodes with an
instance attached should report as consumed here.'

def _node_resources_used(self, node_obj):

    return (node_obj.instance_uuid is not None)
