val unfocus_tac: tactic
val skip_tac: tactic
-val fold_tactic: lowtactic -> tactic
+val distribute_tac: lowtactic -> tactic
+val block_tac: tactic list -> tactic
val apply_tac: tactic_term -> tactic
+val change_tac: tactic_term -> tactic_term -> tactic
val pp_tac_status: tac_status -> unit