1interval_(atomic(A), Res, _Flags),
    2    r_hook(_R, A)
    3 => eval(A, Res1),
    4    clean(Res1, Res).
    5
    6interval_(C, Res, Flags),
    7    C = ci(A, B)
    8 => interval_(A, A1, Flags),
    9    interval_(B, B1, Flags),
   10    Res = ci(A1, B1).
   11
   12instantiate(A, Res),
   13    A =