# File lib/sass/cache_stores/filesystem.rb, line 18
      def _retrieve(key, version, sha)
        return unless File.readable?(path_to(key))
        begin
          File.open(path_to(key), "rb") do |f|
            if f.readline("\n").strip == version && f.readline("\n").strip == sha
              return f.read
            end
          end
          File.unlink path_to(key)
        rescue Errno::ENOENT
          # Already deleted. Race condition?
        end
        nil
      rescue EOFError, TypeError, ArgumentError => e
        Sass::Util.sass_warn "Warning. Error encountered while reading cache #{path_to(key)}: #{e}"
      end