anchor.diff:  
   NOTE: If you are coming from haskell, it represents the `do-syntax` of haskell.
   
  -Let see the same example but translated to more clear code using mlet macto:
  +Let see the same example but translated to more clear code using mlet macro:
   
   [source, clojure]
   ----
  
positive.code: the composition ourselves.
  
  In some circumstances we would like combine the effects of two monads in another one. We call the
  resulting monad a monad transformer, which is the composition of a "base" and a "inner" monad.
  
  Almost every monad implemented in _cats_ has a monad transformer for combining it with
  any other monad.
  
  TODO
  
  
  Clojure Types
  -------------
  
negative.code: [source, clojure]
  ----
  (ns functor.example
    (:require [cats.core :refer [fmap]]
              [cats.monad.maybe :refer [just]])
    (:use [cats.builtin]))
  
  (defn fmap2
  