anchor.diff:  %% Take default params, and also merge in optional params from Params, to return
   %% a proplist of params.
   make_params(ScenarioParams) ->
  -  Protocol = proplists:get_value(protocol, ScenarioParams, "http:"),
  +  Protocol = proplists:get_value(protocol, ScenarioParams, ?DEFAULT_PROTOCOL),
     Port = case Protocol of
  -           "http:"  -> 80;
  -           "https:" -> 443
  +           "http:"  -> ?DEFAULT_PORT_HTTP;
  +           "https:" -> ?DEFAULT_PORT_HTTPS
            end,
     DefaultParams = [ {hostname, "localhost"}
                     , {protocol, Protocol}
  
positive.code: -include_lib("katt/include/blueprint_types.hrl").
  
  %%%_* Defines ==========================================================
  -define(VAR_PREFIX,        "katt_").
  -define(RECALL_BEGIN_TAG,  "{{<").
  -define(RECALL_END_TAG,    "}}").
  -define(STORE_BEGIN_TAG,   "{{>").
  -define(STORE_END_TAG,     "}}").
  -define(MATCH_ANY,         "{{_}}").
  -define(SCENARIO_TIMEOUT,  120000).
  -define(REQUEST_TIMEOUT,   20000).
  
  -type katt_run_result() :: { nonempty_string()    % scenario name
                             , [ { string()         % operation description
  
negative.code: run(Scenario, Params, Options) ->
    ScenarioTimeout = proplists:get_value( scenario_timeout
                                         , Options
                                         , ?DEFAULT_SCENARIO_TIMEOUT
                                         ),
    spawn_link(?MODULE, run, [self(), Scenario, Params, Options]),
    receive {done, Result}    -> Result
  