Uncaught Error: Call to undefined function revo_header_check() in /home/pikko007/public_html/wp-content/themes/revo/header.php on line 5

• require_once()
  wp-includes/template.php:722
• load_template()
  wp-includes/template.php:671
• locate_template()
  wp-includes/general-template.php:41
• get_header()
  wp-content/themes/revo/page.php:1
• include()
  wp-includes/template-loader.php:98
• require_once()
  wp-blog-header.php:19
• require()
  index.php:17