anchor.diff:  %% <?xml version="1.0" encoding="UTF-8"?>
   %%   <Usage>
   %%     <Access>
  -%%       <Node name="riak_moss@127.0.0.1">
  -%%         <Sample StartTime="20120113T194510Z" EndTime="20120113T194520Z">
  -%%           <Operation type="KeyRead">
  -%%             <Count>1</Count>
  -%%             <BytesOut>22</BytesOut>
  -%%           </Operation>
  -%%           <Operation type="KeyWrite">
  -%%             <Count>2</Count>
  -%%             <BytesIn>44</BytesIn>
  -%%           </Operation>
  -%%         </Sample>
  -%%         <Sample StartTime="20120113T194520Z" EndTime="20120113T194530Z">
  -%%           <Operation type="KeyRead">
  -%%             <Count>3</Count>
  -%%             <BytesOut>66</BytesOut>
  -%%           </Operation>
  -%%           <Operation type="KeyWrite">
  -%%             <Count>4</Count>
  -%%             <BytesIn>88</BytesIn>
  -%%           </Operation>
  -%%         </Sample>
  -%%       </Node>
  +%%       <Nodes>
  +%%         <Node name="riak_moss@127.0.0.1">
  +%%           <Sample StartTime="20120113T194510Z" EndTime="20120113T194520Z">
  +%%             <Operation type="KeyRead">
  +%%               <Count>1</Count>
  +%%               <BytesOut>22</BytesOut>
  +%%             </Operation>
  +%%             <Operation type="KeyWrite">
  +%%               <Count>2</Count>
  +%%               <BytesIn>44</BytesIn>
  +%%             </Operation>
  +%%           </Sample>
  +%%           <Sample StartTime="20120113T194520Z" EndTime="20120113T194530Z">
  +%%             <Operation type="KeyRead">
  +%%               <Count>3</Count>
  +%%               <BytesOut>66</BytesOut>
  +%%             </Operation>
  +%%             <Operation type="KeyWrite">
  +%%               <Count>4</Count>
  +%%               <BytesIn>88</BytesIn>
  +%%             </Operation>
  +%%           </Sample>
  +%%         </Node>
  +%%       </Nodes>
  +%%       <Errors/>
   %%     </Access>
   %%   <Storage>not_requested</Storage>
   %% </Usage>
  
positive.code: %%
  %% JSON response looks like:
  %% ```
  %% {"Access":[{"Node":"riak_moss@127.0.0.1",
  %%             "Samples":[{"StartTime":"20120113T194510Z",
  %%                         "EndTime":"20120113T194520Z",
  %%                         "KeyRead":{"Count":1,
  %%                                    "BytesOut":22},
  %%                         "KeyWrite":{"Count":2,
  %%                                     "BytesIn":44},
  %%                        {"StartTime":"20120113T194520Z",
  %%                         "EndTime":"20120113T194530Z",
  %%                         "KeyRead":{"Count":3,
  %%                                    "BytesOut":66},
  %%                         "KeyWrite":{"Count":4,
  %%                                     "BytesIn":88}
  %%                       ]}
  %%           ],
  %%  "Storage":"not_requested"}
  %% '''
  %%
  
negative.code: xml_access(Msg) when is_atom(Msg) ->
      [atom_to_list(Msg)];
  xml_access({Access, Errors}) ->
      Nodes = [{?KEY_NODE, [{name, Node}],
                [xml_sample(S, ?KEY_OPERATION, ?KEY_TYPE) || S <- Samples]}
               || {Node, Samples} <- Access],
      Errs = [ xml_sample_error(E, ?KEY_OPERATION, ?KEY_TYPE)
               || E <- Errors ],
      [{?KEY_NODES, Nodes},
       {?KEY_ERRORS, Errs}].
  
  xml_sample(Sample, SubType, TypeLabel) ->
      {value, {?START_TIME,S}, SampleS} =
  