let add_marks fct_marks nodes_marks =
SlicingParameters.debug ~level:2 "add_marks@.";
let to_prop = FctMarks.mark_and_propagate fct_marks nodes_marks in
FctMarks.mark_visible_output fct_marks;
let to_prop = FctMarks.mark_visible_inputs fct_marks to_prop in
to_prop