EXPORT        M1.

BASE          Day, ListOfDay.

CONSTANT      Nil : ListOfDay;
              Monday, Tuesday, Wednesday, Thursday, Friday, Saturday,
              Sunday : Day.
FUNCTION      Cons : Day * ListOfDay -> ListOfDay.
PREDICATE     Append : ListOfDay * ListOfDay * ListOfDay;
              Append3 : ListOfDay * ListOfDay * ListOfDay * ListOfDay.