how to diff 2 hashes

hash-diff.rb

class Hash
  def diff(other)
    (self.keys + other.keys).uniq.inject({}) do |memo, key|
      unless self[key] == other[key]
        if self[key].kind_of?(Hash) &&  other[key].kind_of?(Hash)
          memo[key] = self[key].diff(other[key])
        else
          memo[key] = [self[key], other[key]] 
        end
      end
      memo
    end
  end
end

a = {"pk"=>"ACE02010-CYYYO", "_id"=>"tui:property:ACE02010-CYYYO", "gid"=>"tui:property:ACE02010-CYYYO", "published"=>false, "hidden"=>false, "meta"=>{"external_source"=>"tui", "external_id"=>"ACE02010-CYYYO", "type"=>"property", "warnings"=>[], "errors"=>[], "valid"=>false, "extra"=>{}, "created_at"=>1223157600.0, "updated_at"=>1223157600.0, "downloaded_at"=>1223157600.0, "api_version"=>"1.0.0"}, "info"=>{"capacity"=>4, "size"=>45, "size_unit"=>"square_meter", "type"=>"apartment", "beds"=>nil, "themes"=>[], "name"=>nil, "stars"=>nil, "extra"=>{"cleaning_fee"=>15.0}}, "facilities"=>["dishwasher", "internet", "family_friendly", "indoor_fireplace", "washer_dryer"], "photos"=>[{"order"=>"0", "url"=>"http://www.tui-ferienhaus.de/bilder/objects/e/ace/ace01001/600/ace01001_02.jpg"}, {"order"=>"1", "url"=>"http://www.tui-ferienhaus.de/bilder/objects/e/ace/ace01001/600/ace01001_05.jpg"}], "location"=>{"address"=>{"city"=>"Costa Teguise", "country"=>"Spain", "country_code"=>"ES", "street"=>nil, "post_code"=>nil}, "geodata"=>{"lat"=>"28.993314", "lng"=>"-13.50121"}, "floor"=>nil, "country"=>"Spain", "country_code"=>"ES", "region"=>nil, "subregion"=>nil, "place"=>nil}, "rooms"=>{"bathrooms"=>{}, "bedrooms"=>{}, "totals"=>{}, "info"=>[]}, "policies"=>[], "localisation"=>{"cs"=>{"description"=>nil, "extra"=>{}}, "da"=>{"description"=>nil, "extra"=>{}}, "de"=>{"description"=>"(de)Apartments Santa Rosa, Costa Teguise - (de)two-room apartment/type 1<br>(de)Malerisch angelegter Ferienpark mit einem großen See.<br>(de)town center 200 m, shopping 50 m, shopping mall 300 m.<br>(de)The photos show examples of houses and accommodation.German-speaking personnel.<br>(de)2-room apt.. living room, (2 sleeping facilities). bedroom, (2 single beds).<br>(de)apartments, rustically and comfortably furnished. on ground floor or upstairs. kitchenette.<br>Hausregeln:<br>Eine Kaution in Hoehe von EUR 500,- ist vor Ort in bar zu hinterlegen.<br>Zusätzliche Kosten:<br>- Endreinigung: 15.00/pro Person/Aufenthalt", "extra"=>{}, "title"=>"(de)Apartments Santa Rosa, Costa Teguise"}, "en"=>{"description"=>"Apartments Santa Rosa, Costa Teguise - two-room apartment/type 1<br>town center 200 m, shopping 50 m, shopping mall 300 m.<br>The photos show examples of houses and accommodation.German-speaking personnel.<br>2-room apt.. living room, (2 sleeping facilities). bedroom, (2 single beds).<br>apartments, rustically and comfortably furnished. on ground floor or upstairs. kitchenette.<br>House rules:<br>A deposit of EUR 5000 is required.<br>We kindly ask you to communicate your flight details specifying outbound and return flight.<br>deposit: 500,00 € (cash)", "extra"=>{}, "title"=>"Apartments Santa Rosa, Costa Teguise"}, "es"=>{"description"=>nil, "extra"=>{}}, "fi"=>{"description"=>nil, "extra"=>{}}, "fr"=>{"description"=>nil, "extra"=>{}}, "hr"=>{"description"=>nil, "extra"=>{}}, "hu"=>{"description"=>nil, "extra"=>{}}, "it"=>{"description"=>nil, "extra"=>{}}, "nl"=>{"description"=>nil, "extra"=>{}}, "no"=>{"description"=>nil, "extra"=>{}}, "pl"=>{"description"=>nil, "extra"=>{}}, "pt"=>{"description"=>nil, "extra"=>{}}, "ru"=>{"description"=>nil, "extra"=>{}}, "sv"=>{"description"=>nil, "extra"=>{}}, "tr"=>{"description"=>nil, "extra"=>{}}}}
b = {"_id"=>"tui:property:ACE02010-CYYYO", "gid"=>"tui:property:ACE02010-CYYYO", "published"=>false, "hidden"=>false, "meta"=>{"external_source"=>"tui", "external_id"=>"ACE02010-CYYYO", "type"=>"property", "api_version"=>"1.0.0", "created_at"=>1223157600.0, "updated_at"=>1223157600.0, "downloaded_at"=>1223157600.0, "extra"=>{}, "warnings"=>[], "errors"=>[], "valid"=>false}, "info"=>{"type"=>"apartment", "capacity"=>4, "beds"=>nil, "themes"=>[], "size"=>45, "size_unit"=>"square_meter", "name"=>nil, "stars"=>nil}, "facilities"=>["dishwasher", "internet", "family_friendly", "indoor_fireplace", "washer_dryer"], "photos"=>[{"order"=>"0", "url"=>"http://www.tui-ferienhaus.de/bilder/objects/e/ace/ace01001/600/ace01001_02.jpg"}, {"order"=>"1", "url"=>"http://www.tui-ferienhaus.de/bilder/objects/e/ace/ace01001/600/ace01001_05.jpg"}], "location"=>{"geodata"=>{"lat"=>"28.993314", "lng"=>"-13.50121"}, "floor"=>nil, "address"=>{"street"=>nil, "city"=>"Costa Teguise", "country"=>"Spain", "post_code"=>nil, "country_code"=>"ES"}, "country"=>"Spain", "country_code"=>"ES", "region"=>nil, "subregion"=>nil, "place"=>nil}, "rooms"=>{"totals"=>{}, "bedrooms"=>{}, "bathrooms"=>{}, "info"=>[]}, "policies"=>[], "localisation"=>{"cs"=>{"description"=>nil, "extra"=>{}}, "da"=>{"description"=>nil, "extra"=>{}}, "de"=>{"description"=>"(de)Apartments Santa Rosa, Costa Teguise - (de)two-room apartment/type 1<br>(de)Malerisch angelegter Ferienpark mit einem großen See.<br>(de)town center 200 m, shopping 50 m, shopping mall 300 m.<br>(de)The photos show examples of houses and accommodation.German-speaking personnel.<br>(de)2-room apt.. living room, (2 sleeping facilities). bedroom, (2 single beds).<br>(de)apartments, rustically and comfortably furnished. on ground floor or upstairs. kitchenette.<br>Hausregeln:<br>Eine Kaution in Hoehe von EUR 500,- ist vor Ort in bar zu hinterlegen.<br>Zusätzliche Kosten:<br>- Endreinigung: 15.00/pro Person/Aufenthalt", "extra"=>{}, "title"=>"(de)Apartments Santa Rosa, Costa Teguise"}, "en"=>{"description"=>"Apartments Santa Rosa, Costa Teguise - two-room apartment/type 1<br>town center 200 m, shopping 50 m, shopping mall 300 m.<br>The photos show examples of houses and accommodation.German-speaking personnel.<br>2-room apt.. living room, (2 sleeping facilities). bedroom, (2 single beds).<br>apartments, rustically and comfortably furnished. on ground floor or upstairs. kitchenette.<br>House rules:<br>A deposit of EUR 5000 is required.<br>We kindly ask you to communicate your flight details specifying outbound and return flight.<br>deposit: 500,00 € (cash)", "extra"=>{}, "title"=>"Apartments Santa Rosa, Costa Teguise"}, "es"=>{"description"=>nil, "extra"=>{}}, "fi"=>{"description"=>nil, "extra"=>{}}, "fr"=>{"description"=>nil, "extra"=>{}}, "hr"=>{"description"=>nil, "extra"=>{}}, "hu"=>{"description"=>nil, "extra"=>{}}, "it"=>{"description"=>nil, "extra"=>{}}, "nl"=>{"description"=>nil, "extra"=>{}}, "no"=>{"description"=>nil, "extra"=>{}}, "pl"=>{"description"=>nil, "extra"=>{}}, "pt"=>{"description"=>nil, "extra"=>{}}, "ru"=>{"description"=>nil, "extra"=>{}}, "sv"=>{"description"=>nil, "extra"=>{}}, "tr"=>{"description"=>nil, "extra"=>{}}}, "pk"=>"ACE02010-CYYYO", "extra"=>{"cleaning_fee"=>15.0}}

puts a.diff(b)
puts b.diff(a)