expand_cache_key

# File activesupport/lib/active_support/cache.rb, line 77
    def self.expand_cache_key(key, namespace = nil)
      expanded_cache_key = namespace ? "#{namespace}/" : ""

      prefix = ENV["RAILS_CACHE_ID"] || ENV["RAILS_APP_VERSION"]
      if prefix
        expanded_cache_key << "#{prefix}/"
      end

      expanded_cache_key <<
        if key.respond_to?(:cache_key)
          key.cache_key
        elsif key.is_a?(Array)
          if key.size > 1
            key.collect { |element| expand_cache_key(element) }.to_param
          else
            key.first.to_param
          end
        elsif key
          key.to_param
        end.to_s

      expanded_cache_key
    end