pub type Coordinate { Coordinate(x: Int, y: Int) }
Coordinate(x: Int, y: Int)
pub fn add(m: Coordinate, n: Coordinate) -> Coordinate
pub fn equal(coordinate_a: Coordinate, coordinate_b: Coordinate) -> Bool
pub fn multiply(m: Coordinate, n: Coordinate) -> Coordinate
pub fn substract(m: Coordinate, n: Coordinate) -> Coordinate