1export function sum(arr: number[]) { 2 return arr.reduce((a, e) => a + e, 0); 3} 4 5export function* cons<T>(arr: T[], size: number) { 6 for (let i = 0; i < arr.length - size + 1; i++) { 7 const chunk = arr.slice(i, i + size); 8 yield chunk; 9 } 10}