anchor.diff:  === First steps
   
   We'll start by using the most basic lens, the identity lens. We can get the value
  -a lens is focused on using the `focus` function in `cats.labs.lens` ns:
  -
  -[source, clojure]
  -----
  -(require '[cats.labs.lens :as l])
  +a lens is focused on using the `focus` function in `lentes.core` ns:
  +
  +[source, clojure]
  +----
  +(require '[lentes.core :as l])
   
   (l/focus l/id [0 1 2 3])
   ;; => [0 1 2 3]
  
positive.code: ;; => 1
  ----
  
  === Interoperability
  
  There are also `Focus` type that allows you to derive atom like objects from
  
negative.code: 
  And do not forget that you also can attach watchers to focused atoms in the same
  way as you will do that with clojure(script) atoms.
  
  
  == Developers Guide
  