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: validator.rb
    path of file: ./repos/truffleruby/lib/mri/rubygems
    
    the code of the file until where you have to start completion: # frozen_string_literal: true
#--
# Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
# All rights reserved.
# See LICENSE.txt for permissions.
#++

require_relative "package"
require_relative "installer"

##
# Val
    
  def alien(gems=[])
    errors = Hash.new {|h,k| h[k] = {} }

    Gem::Specification.each do |spec|
      next unless gems.include? spec.name unless gems.empty?
      next if spec.default_gem?

      gem_name      = spec.file_name
      gem_path      = spec.cache_file
      spec_path     = spec.spec_file
      gem_directory = spec.full_gem_path

      unless File.directory? gem_directory
        errors[gem_name][spec.full_name] =
          "Gem registered but doesn't exist at #{gem_directory}"
        next
      end

      unless File.exist? spec_path
        errors[gem_name][spec_path] = "Spec file missing for installed gem"
      end

      begin
        unless File.readable?(gem_path)
          raise Gem::VerificationError, "missing gem file #{gem_path}"
        end