Markup: Title With Markup

Fatal error: Uncaught Error: Call to undefined function dmestairlift_posted_on() in /www/wp-content/themes/dmestairlift/template-parts/content.php:25 Stack trace: #0 /www/wp-includes/template.php(732): require() #1 /www/wp-includes/template.php(676): load_template('/www/wp-content...', false, Array) #2 /www/wp-includes/general-template.php(204): locate_template(Array, true, false, Array) #3 /www/wp-content/themes/dmestairlift/single.php(20): get_template_part('template-parts/...', 'post') #4 /www/wp-includes/template-loader.php(106): include('/www/wp-content...') #5 /www/wp-blog-header.php(19): require_once('/www/wp-include...') #6 /www/index.php(17): require('/www/wp-blog-he...') #7 {main} thrown in /www/wp-content/themes/dmestairlift/template-parts/content.php on line 25