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: that not acts like containers. As example, clojure keywords are values but can not be containers, so
  that, their should not extend previously explained protocols.
  
  Vector
  ~~~~~~
  
  TODO
  
  List
  ~~~~
  
  TODO
  
  Set
  ~~~
  
  TODO
  
  
  License
  -------
  
negative.code: MonadPlus
  ~~~~~~~~~
  
  The link:http://www.haskell.org/haskellwiki/MonadPlus_reform_proposal#MonadPlus[MonadPlus] protocol
  represents a MonadZero wich has a plus operation.
  
  .MonadPlus protocol
  [source, clojure]
  