anchor.diff:  
       % Send Header (including signed checksum)
       HeaderFrame = pushy_messaging:make_header(proto_v2, SessionMethod, SessionKey, BodyFrame),
  +    Now = pushy_time:timestamp(),
  +    folsom_metrics:notify({?INTERVAL_METRIC, pushy_time:diff_in_secs(LastTimestamp, Now)}),
       pushy_messaging:send_message(Sock, [HeaderFrame, BodyFrame]),
  -    lager:debug("Heartbeat sent: header=~s,body=~s",[HeaderFrame, BodyFrame]),
  -    State#state{sequence=Sequence + 1}.
  +    lager:debug("Heartbeat sent: ~s,sequence=~p",[NodeName, Sequence]),
  +    State#state{sequence=Sequence + 1,
  +                heartbeat_timestamp=Now}.
   
   -spec send_response(Type :: binary(),
                       JobId :: binary(),
  
positive.code: -include_lib("pushy_common/include/pushy_metrics.hrl").
  -include_lib("public_key/include/public_key.hrl").
  
  
  %% ------------------------------------------------------------------
  %% API Function Exports
  
negative.code:          heartbeat_sock :: any(),
           org_name :: binary(),
           heartbeat_interval :: integer(),
           heartbeat_timestamp :: integer(),
           sequence :: integer(),
           server_public_key :: rsa_public_key(),
           session_key :: binary(),
  