format (MiniMagick::Image)

    # File lib/mini_magick.rb, line 83
        def format(format, page=0)
          run_command("mogrify", "-format", format, @path)

          old_path = @path.dup
          @path.sub!(/(\.\w+)?$/, ".#{format}")
          File.delete(old_path) unless old_path == @path

          unless File.exists?(@path)
            begin
              FileUtils.copy_file(@path.sub(".#{format}", "-#{page}.#{format}"), @path)
            rescue e
              raise MiniMagickError, "Unable to format to #{format}; #{e}" unless File.exist?(@path)
            end
          end
        ensure
          Dir[@path.sub(/(\.\w+)?$/, "-[0-9]*.#{format}")].each do |fname|
            File.unlink(fname)
          end
        end