anchor.diff:  % delete(state(), Key :: binary()) ->
   %   ok | {error, Reason :: term()}
   % key must be 160b
  -delete(State, Key) ->
  -    File = location(State,Key),
  +delete(State, BKey) ->
  +    File = location(State,BKey),
       case file:delete(File) of
           ok -> ok;
           {error, enoent} -> ok;
  
positive.code: % @doc riak_fs_backend is a simple filesystem storage system.
  
  -module(riak_fs_backend).
  -export([start/1,stop/1,get/2,put/3,list/1,delete/2]).
  % @type state() = term().
  -record(state, {dir}).
  
  
negative.code: % get(state(), Key :: binary()) ->
  %   {ok, Val :: binary()} | {error, Reason :: term()}
  % key must be 160b
  get(State, BKey) ->
      File = location(State,BKey),
      case filelib:is_file(File) of
          false -> {error, notfound};
          true -> file:read_file(File)
  