+ val first: tactics: (string * tactic) list -> tactic
+ val thens: start: tactic -> continuations: tactic list -> tactic
+ val then_: start: tactic -> continuation: tactic -> tactic
+ val seq: tactics: tactic list -> tactic (** "folding" of then_ *)
+ val repeat_tactic: tactic: tactic -> tactic
+ val do_tactic: n: int -> tactic: tactic -> tactic
+ val try_tactic: tactic: tactic -> tactic
+ val solve_tactics: tactics: (string * tactic) list -> tactic