anchor.diff:  %%
   -spec return(A) -> m(A).
   
  -return(_) ->
  -   fun http_io/1.
  +return(X) ->
  +   m_state:return(X).
   
   %%
   %%
  
positive.code:       <<"close">> ->
           [Pckt|maps:remove(http, State)];
        _           ->
           Url       = uri:new(lens:get(url(), State)),
           Authority = uri:authority(Url),
           [Pckt|maps:remove(http, State#{Authority => Sock})]
     end.
  
negative.code: %%   IO-monad: http 
  -module(k_http).
  -compile({parse_transform, category}).
  
  -include("knet.hrl").
  -include_lib("datum/include/datum.hrl").
  
  -export([return/1, fail/1, '>>='/2]).
  -export([
     new/1, new/2, 
     x/1, method/1, 
     h/2, header/2, 
     d/1, payload/1, 
     r/0, request/0, request/1
  ]).
  
  -type m(A)    :: fun((_) -> [A|_]).
  -type f(A, B) :: fun((A) -> m(B)).
  