-( 12:54:48 )-< command 0 >------------------{ counter: 0 }-
utop # type no_tuple = NT of int * int;; 
type no_tuple = NT of int * int
-( 12:54:48 )-< command 1 >------------------{ counter: 0 }-
utop # type tuple = T of (int * int);;
type tuple = T of (int * int)
-( 12:55:38 )-< command 2 >------------------{ counter: 0 }-
utop # let a = 12, 34;;
val a : int * int = (12, 34)
-( 12:55:48 )-< command 3 >------------------{ counter: 0 }-
utop # T a;;
- : tuple = T (12, 34)
-( 12:56:05 )-< command 4 >------------------{ counter: 0 }-
utop # NT a;;
Error: The constructor NT expects 2 argument(s),
       but is applied here to 1 argument(s)