type t = Stdlib.Lexing.position * Stdlib.Lexing.position
val dummy : Stdlib.Lexing.position * Stdlib.Lexing.position
val union : (Stdlib.Lexing.position * Stdlib.Lexing.position)->(Stdlib.Lexing.position * Stdlib.Lexing.position)->Stdlib.Lexing.position * Stdlib.Lexing.position