let filter_one_output (oe: output_event) (run_lev: level) (levs: level list)
: output_event list =
let lev_oe = (label_output oe) in
if (lev_oe = run_lev) then [oe]
else
( if (leq run_lev lev_oe) then
( if (List.mem lev_oe levs)
then []
else [oe] )
else [] )