class Aws::Binary::EventStreamEncoder

def encode(event_type, params)
  if event_type == :end_stream
    payload = ''
  else
    payload = @encoder.encode(@event_builder.apply(event_type, params))
  end
  headers, signature = @signer.sign_event(@prior_signature, payload, @encoder)
  @prior_signature = signature
  message = Aws::EventStream::Message.new(
    headers: headers,
    payload: StringIO.new(payload)
  )
  @encoder.encode(message)
end