Suite = Class { "Heart", "Diamond", "Spade", "Club" }
Suite.
    is_heart self = self::base == "Heart"

h = Suite.new "Heart"
d = Suite.new "Diamond"
assert h.is_heart()
assert not d.is_heart()

Month = Class 1..12
Month.
    is_first_half self = self::base <= 6

jan = Month.new 1
dec = Month.new 12
assert jan.is_first_half()
assert not dec.is_first_half()

Nat8 = Inherit 0..255
Nat8.
    as_ascii self = chr self
    satuating_add self, other: Nat =
        if self + other >= 0 and self + other <= 255:
            do: Nat8.new self + other
            do: Nat8.new 255

n = Nat8.new 97
_: Nat = n + 2
assert n.as_ascii() == "a"
assert n.satuating_add(300) == 255