let make ?(a=false) ?(d=false) ?(c=false) _ =
match a,d,c with
| false, false, false -> 0x000
| true, false, false -> 0x100
| false, true, false -> 0x010
| false, false, true -> 0x001
| true, true, false -> 0x110
| true, false, true -> 0x101
| false, true, true -> 0x011
| true, true, true -> 0x111