code: function filterAfter(posts) {
        after = moment(after.replace(/\//g, '-'), 'MM-DD-YYYY', true);
        if (!after.isValid()) {
          console.log(chalk.red('After date is not valid (expecting `MM-DD-YYYY`), ignoring argument.'));
          return posts;
        }
  
        return posts.filter(function filterPosts(post) {
          return moment(post.date).isAfter(after);
        });
      }
docs: filter the posts using an after date if supplied