anchor.diff:  -include_lib("couch_mrview/include/couch_mrview.hrl").
   
   % /db/_design/foo/_show/bar/docid
  -% show converts a json doc to a response of any content-type. 
  +% show converts a json doc to a response of any content-type.
   % it looks up the doc an then passes it to the query server.
   % then it sends the response from the query server to the http client.
   
  
positive.code: handle_doc_show_req(#httpd{
          path_parts=[_, _, _, _, ShowName, DocId|Rest]
      }=Req, Db, DDoc) ->
      
      DocParts = [DocId|Rest],
      DocId1 = ?l2b(string:join([?b2l(P)|| P <- DocParts], "/")),
  
  
negative.code:     chttpd:etag_respond(Req, CurrentEtag, fun() ->
          JsonReq = chttpd_external:json_req_obj(Req, Db, DocId),
          JsonDoc = couch_query_servers:json_doc(Doc),
          [<<"resp">>, ExternalResp] =
              couch_query_servers:ddoc_prompt(DDoc, [<<"shows">>, ShowName],
                  [JsonDoc, JsonReq]),
          JsonResp = apply_etag(ExternalResp, CurrentEtag),
  