How to use the @mapbox/batfish/data/horse-names.join function in @mapbox/batfish

{this.props.frontMatter.description}
        
        <div>
          <div>Posts</div>
          {posts.map(post =&gt; {
            return (
              <div>
                <a href="{post.path}">
                  {post.frontMatter.title}
                </a>
              </div>
            );
          })}
        </div>
        <div style="{{">
          Horse names: {horseNames.join(', ')}
        </div>
      
    );
  }
}