code: protected function compileMarkdownEchos($value)
      {
          $pattern = sprintf('/(@)?%s\s*(.+?)\s*%s(\r?\n)?/s', $this->markdownTags[0], $this->markdownTags[1]);
  
          $callback = function ($matches) {
              $wrapper = sprintf($this->markdownFormat, $this->compileEchoDefaults($matches[2]));
  
              return $matches[1] ? strlen(stripcslashes($this->markdownTags[0])) > 2 ? $matches[0] : substr($matches[0], 1) : '<?php echo '.$wrapper.'; ?>';
          };
  
          return preg_replace_callback($pattern, $callback, $value);
      }
docs: Compile markdown into valid html.
  
  @param  string  $value
  @return string