anchor.diff:  
       RegExp empty_line = new RegExp(r"^\s*$", multiLine: true);
       RegExp paragraph_regex = new RegExp(r"(^.*[^\s]+.*\n?)+", multiLine: true);
  +    
       regular_expressions.add(new markdown_regex(paragraph_regex, (Match found) {
                   return new markdown_paragraph(found.group(0));
       }, process: generate_markdown_paragraphs));
  
positive.code: 
      if (!found_match) {
          if (content.length > 0) {
              ret.add(new markdown_plaintext(content));
          }
          return ret;
  
negative.code: }
  
  class markdown_emphasis extends markdown_node {
      markdown_emphasis(String content) : super() {
          children.add(new markdown_plaintext(content));
      }
  
      String generate_html() {
          String ret = "<em>";
          for (markdown_node cur in children) {
              ret = "${ret}${cur.generate_html()}";
          }
          ret = "${ret}</em>";
          return ret;
  