anchor.diff:  
   === From Value
   
  -It creates a observable sequence of one unique value:
  +It creates an observable sequence of one unique value:
   
   [source, clojure]
   ----
  
positive.code: 
  === Flat Map
  
  Convets a observable seequence that can contain other observable seequences in
  an other observable seequences that emits just plain values.
  
  The result is similar to concatenate all the underlying seequences.
  
  [source, clojure]
  ----
  
negative.code: 
  === Slice
  
  This is a some kind of combination of `skip` and `take`, and returns an observable
  sequence that represents a portion delimited by start and end of the source
  observable sequence.
  
  [source, clojure]
  ----
  