text: let n = function(digit) {
    return function(oper) {
      return oper ? oper(digit) : digit;
    }
  };
  let zero = n(0);
  let one = n(1);
  let two = n(2);
  let three = n(3);
  let four = n(4);
  let five = n(5);
  let six = n(6);
  let seven = n(7);
  let eight = n(8);
  let nine = n(9);
   
  function plus(r) { return function(l) { return l + r; }; }
  function minus(r) { return function(l) { return l - r; }; }
  function times(r) { return function(l) { return l * r; }; }
  function dividedBy(r) { return function(l) { return Math.floor(l / r); }; }
  