     end
   end
 
-  @spec oneway(pid, String.t, data, options) :: :ok
+  @spec oneway(pid, String.t, iodata, options) :: :ok
   @doc """
   Execute a one way RPC. One way RPC calls do not generate a response,
   and as such, this implementation uses `GenServer.cast`.

    :ok
  end

  @spec call(pid, String.t, data, module, options) :: protocol_response
  @doc """
  Executes a Thrift RPC. The data argument must be a correctly formatted
  Thrift message.


  @type protocol_response :: success | error

  @type tcp_opts :: [
    timeout: pos_integer,
    send_timeout: integer,
