var result = [5,10]
  |> (_ => _.map(x => x * 2))
  |> (_ => _.reduce( (a,b) => a + b ))
  |> (sum => sum + 1)

expect(result).toBe(31);


var inc = (x) => x + 1;
var double = (x) => x * 2;

var result2 = [4, 9].map( x => x |> inc |> double )

expect(result2).toEqual([10, 20]);