def process_pres (out)
      out.gsub /(<pre\b[^>]*?>([\s\S]*?)<\/pre>)\s*/i do
        pre = $2
        m = $1
        pre_compressed = pre.lines.map{ |l| l.gsub(/\s+$/, '') }.join("\n")
        pre_compressed = HtmlPress.entities_compressor pre_compressed
        m.gsub!(pre, pre_compressed)
        reserve m
      end
    end
def process_pres (out)
      out.gsub /(<pre\b[^>]*?>([\s\S]*?)<\/pre>)\s*/i do
        pre = $2
        m = $1
        pre_compressed = pre.lines.map{ |l| l.gsub(/\s+$/, '') }.join("\n")
        pre_compressed = HtmlPress.entities_compressor pre_compressed
        m.gsub!(pre, pre_compressed)
        reserve m
      end
    end
replace PREs with placeholders