anchor.diff:  PHPStartEchoInsideQuoteString:
   	PhpStartEchoFragment -> type(Echo), pushMode(PHP);
   PHPStartInsideQuoteString:
  -	PhpStartFragment -> channel(SkipChannel), pushMode(PHP);
  +	PhpStartFragment -> skip, pushMode(PHP);
   HtmlEndQuoteString: '\'' '\''? -> popMode;
   HtmlQuoteString: ~[<']+;
   ErrorHtmlQuote: . -> channel(ErrorLexem);
  
positive.code: 
  PHPStartEchoInside:
  	PhpStartEchoFragment -> type(Echo), pushMode(PHP);
  PHPStartInside:
  	PhpStartFragment -> channel(SkipChannel), pushMode(PHP);
  HtmlClose:
  	'>' {
      this.popMode();
  
negative.code: PHPEndSingleLineComment: '?' '>';
  CommentQuestionMark:
  	'?' -> type(Comment), channel(PhpComments);
  CommentEnd: [\r\n] -> skip, popMode; // exit from comment.
  
  mode HereDoc; // TODO: interpolation for heredoc strings.
  
  