1:- use_module(cleaning).    2
    3interval(Expr, Res) :-
    4    interval(Expr, Res, []).
    5
    6interval(Expr, Res1, Flags) :-
    7    clean(Expr, Expr1),
    8    default_digits(Dig, Flags),
    9    interval_(Expr1, Res0, [digits(Dig) | Flags]),
   10    unwrap(Res0, Res1).
   11
   12default_digits(Dig, Flags) 
   13 => ( nb_current(digits, Dig1)
   14    -> true
   15    ; Dig1 = 2
   16    ),
   17    option(digits(Dig), Flags, Dig1)