Pcoq.Ruleval stop : ( 'self, Gramlib.Grammar.norec, 'r, 'r ) tval next : 
  ( 'self, _, 'a, 'r ) t ->
  ( 'self, _, 'b ) Symbol.t ->
  ( 'self, Gramlib.Grammar.mayrec, 'b -> 'a, 'r ) tval next_norec : 
  ( 'self, Gramlib.Grammar.norec, 'a, 'r ) t ->
  ( 'self, Gramlib.Grammar.norec, 'b ) Symbol.t ->
  ( 'self, Gramlib.Grammar.norec, 'b -> 'a, 'r ) t