type Accumulator[Self] = (Self <: Accumulator[Self]) & {
	member add : Int -> Self
}

type MyAccum = {
	member add : Int -> MyAccum
}

assert MyAccum <: Accumulator[MyAccum]





type Acchmmmmulator[Self] = (Self <: Acchmmmmulator[Self]) => {
	member add : Int -> Self
}