anchor.diff:  ;; => 120
   ----
   
  -And conditional lenses that can be defined using a predicate function and
  -returns a lens that focuses in an element only if it passes the predicate:
  +
  +==== Conditionals
  +
  +And conditional lenses that can be defined using a predicate function and returns a
  +lens that focuses in an element only if it passes the predicate:
   
   .Example focusing using conditional lenses
   [source, clojure]
  
positive.code: 
  == Introduction
  
  This is an implementation of functional references modeled as functions (in the
  same way as transducers).
  
  Functional reference or lense is a generalization of get and put mapping to the
  particular part of a data structure, where the result is called _view_ or _focus_
  and the container is usually called _source_.
  
  NOTE: This documentation does not covers all api, so if you miss some function,
  contributions are very welcome. You can see the full link:api/index.html#id[API documentation here].
  
negative.code: ----
  
  
  ==== Associative data structures
  
  There's `key` and `select-keys` for focusing on one or multiple keys respectively:
  
  