class Err(def msg: Str): Exception(msg)
def f(x: Int) -> Int raise[Err] => if x > 0 then return 10 else raise Err("Expected positive number.")
def g() -> Int raise[Err] => raise Err("Error always raised")
def h(x: Int) -> Int raise[Err] => if x < 0 then raise Err("Less than") else raise Err("Greater Than")
f(10)