Updating Dual Function to Data-Last Format

const sum: {
  (that: number): (self: number) => number
  (self: number, that: number): number
} = dual(2, (that: number) => (self: number): number => self + that)

const sum: {
  (that: number): (self: number) => number
  (self: number, that: number): number
} = dual(2, (self: number, that: number): number => self + that)