docs: function () {
              return [
                          __.map (       111 ,   _.appends ('bar')).assert (       '111bar'),
                          __.map (      [222],   _.appends ('bar')).assert (      ['222bar']),
                          __.map (    __(333),   _.appends ('bar')).assert (       '333bar'),
                          __.map ({ foo: 444 },  _.appends ('bar')).assert ({ foo: '444bar' }),
                          __.map ({ foo: 555 }, __.constant ('bar')).assert ({ foo: 'bar' }),
  
                          __.map ({ foo: Promise.resolve (111), bar: Promise.resolve (222) }).assert ({ foo: 111, bar: 222 }),
  
                          __.map (['a','b','c','d','e'],
                              function (x,i) { return Promise.resolve ([i,x]).delay (10 - i) })
                                  .assert ([[0,'a'], [1,'b'], [2,'c'], [3,'d'], [4,'e']]) ] }