anchor.diff:  This generic decorator can be used to easily implement condition checking,
   logging, locking, and so on. It can be more interesting if you want to provide
   several functionalities, instead of stacking more specific decorators, since
  -stacking, or decorator composition, adds indirection levels and deepen the call 
  +stacking, or decorator composition, adds indirection levels and deepen the call
   stack.
   
   //>>>
  
positive.code: function mul = |v| -> 10 * v
  ----
  
  Several factory functions are available in 
  link:./golodoc/gololang/Decorators[`gololang.Decorators`] to ease the creation 
  of checkers:
  
  * `any` is a void checker that does nothing. It can used when you need to check
  
negative.code: 
  == Decorators ==
  
  Golo features Python-like decorators.
  
  === Presentation ===
  //<<<
  