xml2json with base64 decoding

xml2json.rb

require "rubygems"
require "crack"
require "json"
require "base64"

myXML  = Crack::XML.parse(File.read(ARGV[0]))
def decode_base64(parent, myHash)
  myHash.each {|key, value|
    if value.is_a?(Hash)
      decode_base64(key, value)
    elsif value.is_a? String and value.include? "__base64__"
      value.slice!("__base64__")
      myHash[key] = Base64.decode64(value)
    end
  }
end
decode_base64(nil, myXML)
print JSON.pretty_generate(myXML)