accessing variable bindings

[Huayi Huang]

Hi,

I was wondering how I can go about access the variables and their bindings at any stage of the Prolog proof process,  I found the prolog_trace_interception/4 predicate,  however, I couldn't figure out how to get at ALL the variables being used and their bindings at each stage of the trace interception.   Please could someone point me in the right direction?

Many Thanks
Huayi Huang