what arguments for inline C functions in varnish

Question

I found in varnish book that varnish 3 purge functionality could be somehow achieved in varnish 2.1 by

C{ VRT_Nuke(...); }C

signature of VTR_Nuke seems to be

int VRT_nuke(struct sess *sp, const char *str, ...)

in my default.vcl I want to write something like:

sub vcl_hit {
    C{ VRT_Nuke(...); }C
    error 200 "Purged";
}

what arguments should I give the VRT_Nuke function?