   # batch.add({name: 'Evan', home: 'San Francisco'}, 482698020);
   # ```
 
-  add: (data, timestamp = Math.round((new Date).getTime() / 1000)) ->
-    data.timestamp = timestamp
+  add: (data, timestamp) ->
     @_transformData data
+    data.timestamp ?= Math.round((new Date).getTime() / 1000)
 
     @queue.add data
 


  _transformData: (data) ->
    data.identity = data._p

    switch data.type
      when 'record' then data.event = data._n

  # HTTP API.
  #
  # * `_p` (person) is replaced by `identity`
  # * `_t` (timestamp) is replaced by `timestamp`
  # * `record` queries use the `event` property instead of `_n`
  # * `alias` queries use the `alias` property instead of `_n`
  # * `_k` (API key) is replaced by an HTTP header
