anchor.diff:  data: get/set headers and read the body (explained in previous sections).
   
   For compensate this, _catacumba_ comes with special chain handler that populates the context with
  -basic request properties such as, headers, path and method: `basic-request` and let see how you can use
  -it on your application:
  +basic request properties such as, headers, path and method:
   
   [source, clojure]
   ----
  
positive.code: | Mandatory & Regex | `:«token-name»:«regex»` | `[:get "foo/:id:\d+" handler]` | `/foo/2`
  | Optional & Regex | `:«token-name»?:«regex»` | `[:get "foo/:id?:\d+" handler]` | `/foo/2` and `/foo`
  |===========================================================================
  
  
  === Context
  
negative.code:             [:by-method "users"
               [:get list-users-handler]
               [:post create-users-handler]]])
  ----
  
  
  