anchor.diff:  This is a very basic example of the state monad, it has a lot of use cases and explaining all them
   seems out of the scope of this document.
   
  -However, if you have better examples to explain the state monad, documentation for another monad or 
  +However, if you have better examples to explain the state monad, documentation for another monad or
   any other contribution is always welcome.
   
   License
  
positive.code: ;; => #<Nothing >
  ----
  
  Moreover, the applicative functor protocol comes with another function: `pure`. The main purpose of 
  this function is, given any value in a context and new value, wrap the new value in a minimal context of the same
  type as the first argument.
  
  
negative.code: ;; => #<Just [2]>
  ----
  
  The `return` or `pure` functions, when called with one argument, try to use the dynamic scope context value
  that's set internaly by the `bind` function. Therefore you can't use them with one argument out of a `bind` context.
  
  And finally, to make more powerful monadic compositions, _cats_ comes with the `mlet` macro that
  if you are coming from haskell, represents a `do-syntax`:
  