`type xinstr =`

1. `| Instr of instr`
2. `| Last of last`

`val expr : Stdlib.Format.formatter -> expr -> unit`
`val constant : Stdlib.Format.formatter -> constant -> unit`
`val var_list : Stdlib.Format.formatter -> Var.t list -> unit`
`val instr : Stdlib.Format.formatter -> instr -> unit`
`val block : Stdlib.Format.formatter -> (Addr.t -> xinstr -> string) -> int -> block -> unit`
`val program : Stdlib.Format.formatter -> (Addr.t -> xinstr -> string) -> program -> unit`
`val last : Stdlib.Format.formatter -> last -> unit`
`val cont : Stdlib.Format.formatter -> cont -> unit`