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: utils.rb
    path of file: ./repos/metasploit-framework/lib/rex/proto/kerberos/crypto
    
    the code of the file until where you have to start completion: module Rex
  module Proto
    module Kerberos
      mod
    
          def xor_bytes(l1,l2)
            result = []
            l1.zip(l2).each do |b1,b2|
              if b1 != nil && b2 != nil
                result.append((b1^b2))
              end
            end