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: ec2.rb
    path of file: ./repos/ohai/lib/ohai/plugins
    
    the code of the file until where you have to start completion: # frozen_string_literal: true
#
# Author:: Tim Dysinger (<tim@dysinger.net>)
# Author:: Benjamin Black (<bb@chef.io>)
# Author:: Christopher Brown (<cb@chef.io>)
# Author:: Tim Smith (<tsmith@chef.io>)
# Copyright:: 
    
  def has_ec2_xen_dmi?
    # detect a version of '4.2.amazon'
    if file_val_if_exists("/sys/class/dmi/id/bios_version").to_s.include?("amazon")
      logger.trace("Plugin EC2: has_ec2_xen_dmi? == true")
      true
    else
      logger.trace("Plugin EC2: has_ec2_xen_dmi? == false")
      false
    end