text: const mdContainer = require('markdown-it-container');
  
  module.exports = md => {
    md.use(mdContainer, 'demo', {
      validate(params) {
        return params.trim().match(/^demo\s*(.*)$/);
      },
      render(tokens, idx) {
        const m = tokens[idx].info.trim().match(/^demo\s*(.*)$/);
        if (tokens[idx].nesting === 1) {
          const description = m && m.length > 1 ? m[1] : '';
          const content = tokens[idx + 1].type === 'fence' ? tokens[idx + 1].content : '';
          return `<demo-block>
          ${description ? `<div>${md.render(description)}</div>` : ''}
          <!--link-demo: ${content}:link-demo-->
          `;
        }
        return '</demo-block>';
      }
    });
  
    md.use(mdContainer, 'tip');
    md.use(mdContainer, 'warning');
  };
  