You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: failed_delivery_attempt.rb
    path of file: ./repos/grocer/lib/grocer
    
    the code of the file until where you have to start completion: module Grocer
  class FailedDeliveryAttempt
    LENGTH = 38

    attr_accessor :timestamp, :device_tok
    
    def initialize(binary_tuple)
      # N   =>  4 byte timestamp
      # n   =>  2 byte token_length
      # H64 => 32 byte device_token
      seconds, _, @device_token = binary_tuple.unpack('NnH64')
      raise InvalidFormatError unless seconds && @device_token
      @timestamp = Time.at(seconds)
    end