let fold_calls f ff ff_marks acc =
let do_it call (c_opt,sgn) a =
let info = match c_opt with
| None | Some (None) -> ((ff, call), None, sgn)
| Some (Some f) -> ((ff, call), Some f, sgn)
in f call info a
in
PdgIndex.FctIndex.fold_calls do_it ff_marks acc