dec Number.Add : [<a: number> (a) a] a
dec Number.Div : [<a: number> (a) a] a
dec Number.Mul : [<a: number> (a) a] a
dec Number.Neg : [<a: signed> a] a
dec Number.Sub : [<a: signed> (a) a] a
dec Number.Zero : [type a: number] a