stamp_checkout_html_element_once

See hook in action

See this hook used in plugins:

Select Pluginwoocommerce.9.0.2woocommerce.9.1.2woocommerce.9.1.4woocommerce.9.2.2woocommerce.9.2.3woocommerce.9.3.1woocommerce.9.3.3woocommerce.9.4.2woocommerce.9.4.3woocommerce.9.5.1woocommerce.9.5.2woocommerce.9.7.0woocommerce.9.7.1woocommerce.9.8.1woocommerce.9.9.3woocommerce.9.9.5woocommerce.10.0.4woocommerce.10.1.2woocommerce.10.2.2