function intoExample () {
  var inc = function(n: number) { return n+1; };
  var isEven = function(n: number) { return n % 2 == 0; };
  var apush = function(arr: number[], x: number) { arr.push(x); return arr; };
  var xf = t.comp(t.map(inc),t.filter(isEven));
  t.into([], xf, [1,2,3,4]); // [2,4]
}
function catExample () {
  var reverse = function(arr: number[]) {
    var arr: number[] = Array.prototype.slice.call(arr, 0);
    arr.reverse();
    return arr;
  };
  var xf = t.comp(t.map(reverse), t.cat);
  t.into([], xf, [[3,2,1],[6,5,4]]); // [1,2,3,4,5,6]
}
 it('transduces Map without initial values', () => {
   let m1 = Map({a: 1, b: 2, c: 3, d: 4});
   let xform = t.comp(
     t.filter(([k, v]) => v % 2 === 0),
     t.map(([k, v]) => [k, v * 2]),
   );
   let m2 = t.transduce(xform, Map(), m1);
   expect(m1.toObject()).toEqual({a: 1, b: 2, c: 3, d: 4});
   expect(m2.toObject()).toEqual({b: 4, d: 8});
 });
 it('transduces Set without initial values', () => {
   let s1 = Set.of(1, 2, 3, 4);
   let xform = t.comp(
     t.filter(x => x % 2 === 0),
     t.map(x => x + 1),
   );
   let s2 = t.transduce(xform, Set(), s1);
   expect(s1.toArray()).toEqual([1, 2, 3, 4]);
   expect(s2.toArray()).toEqual([3, 5]);
 });
 it('transduces List without initial values', () => {
   let v = List.of(1, 2, 3, 4);
   let xform = t.comp(
     t.filter(x => x % 2 === 0),
     t.map(x => x + 1),
   );
   let r = t.transduce(xform, List(), v);
   expect(v.toArray()).toEqual([1, 2, 3, 4]);
   expect(r.toArray()).toEqual([3, 5]);
 });
 it('transduces Stack without initial values', () => {
   let s = Stack.of(1, 2, 3, 4);
   let xform = t.comp(
     t.filter(x => x % 2 === 0),
     t.map(x => x + 1),
   );
   let s2 = t.transduce(xform, Stack(), s);
   expect(s.toArray()).toEqual([1, 2, 3, 4]);
   expect(s2.toArray()).toEqual([5, 3]);
 });
 it('transduces Set with initial values', () => {
   let s1 = Set.of(1, 2, 3, 4);
   let s2 = Set.of(2, 3, 4, 5, 6);
   let xform = t.comp(
     t.filter(x => x % 2 === 0),
     t.map(x => x + 1),
   );
   let s3 = t.transduce(xform, Set(), s1, s2);
   expect(s1.toArray()).toEqual([1, 2, 3, 4]);
   expect(s2.toArray()).toEqual([2, 3, 4, 5, 6]);
   expect(s3.toArray()).toEqual([1, 2, 3, 4, 5, 7]);
 });
 it('transduces Map with initial values', () => {
   let m1 = Map({a: 1, b: 2, c: 3});
   let m2 = Map({a: 4, b: 5});
   let xform = t.comp(
     t.filter(([k, v]) => v % 2 === 0),
     t.map(([k, v]) => [k, v * 2]),
   );
   let m3 = t.transduce(xform, Map(), m1, m2);
   expect(m1.toObject()).toEqual({a: 1, b: 2, c: 3});
   expect(m2.toObject()).toEqual({a: 4, b: 5});
   expect(m3.toObject()).toEqual({a: 8, b: 2, c: 3});
 });
 it('transduces List with initial values', () => {
   let v1 = List.of(1, 2, 3);
   let v2 = List.of(4, 5, 6, 7);
   let xform = t.comp(
     t.filter(x => x % 2 === 0),
     t.map(x => x + 1),
   );
   let r = t.transduce(xform, List(), v1, v2);
   expect(v1.toArray()).toEqual([1, 2, 3]);
   expect(v2.toArray()).toEqual([4, 5, 6, 7]);
   expect(r.toArray()).toEqual([1, 2, 3, 5, 7]);
 });
 it('transduces Stack with initial values', () => {
   const v1 = Stack.of(1, 2, 3);
   const v2 = Stack.of(4, 5, 6, 7);
   const xform = t.comp(
     t.filter(x => x % 2 === 0),
     t.map(x => x + 1),
   );
   const r = t.transduce(xform, Stack(), v1, v2);
   expect(v1.toArray()).toEqual([1, 2, 3]);
   expect(v2.toArray()).toEqual([4, 5, 6, 7]);
   expect(r.toArray()).toEqual([7, 5, 1, 2, 3]);
 });