anchor.diff:  Maybe
   ~~~~~
   
  -Two most common wrapper is "Maybe" (commonly named Optional on not functional programming
  +
  +This is one of the two most used monad types (commonly named Optional on not functional programming
   languages).
   
   Maybe/Optional is a polymorphic type that represents encapsulation of an optional value; e.g. it is
  
positive.code: ;; => #<Just [2]>
  ----
  
  Same example but applying function over Nothing:
  
  [source, clojure]
  ----
  
negative.code: ;; => true
  ----
  
  When a monad instance implements the MonadZero protocol, `:when` clauses can be used in `mlet`
  bindings:
  
  [source, clojure]
  ----
  