anchor.diff:                  vnode_master :: atom(),
                   plan_fun :: function(),
                   process_fun :: function(),
  -                coverage_plan_mod :: module()
  +                coverage_plan_fn :: function()
                  }).
   
   -callback init(From::from(), RequestArgs::any()) ->
  
positive.code:       From={_, ReqId, _},
        RequestArgs]) ->
      {Request, VNodeSelector, NVal, PrimaryVNodeCoverage,
       NodeCheckService, VNodeMaster, Timeout, PlannerMod, ModState} =
          Mod:init(From, RequestArgs),
      maybe_start_timeout_timer(Timeout),
      PlanFun = plan_callback(Mod),
  
negative.code:                                       timeout=Timeout,
                                        vnode_master=VNodeMaster,
                                        plan_fun = PlanFun,
                                        coverage_plan_fn = CoveragePlanFn}) ->
      CoveragePlan = find_plan(CoveragePlanFn,
                               VNodeSelector,
                               NVal,
                               PVC,
  