How do I use 'vars_to_restore' and 'vars_to_freeze'

[Endousan]

I have a trained model and want to used to a new model, they have some same layer, so I try to transfer weights of these layers and freeze them, but know few about it. after reading niftynet documentation, I still don't know how 'vars_to_restore' and 'vars_to_freeze' is called after it is written in the configuration. Are there some relevant example reference?
thanks a lot