How can nonce variables generated by WordPress be correctly inserted as variables in PHP headers for Content Security Policy?

Nonce variables generated by WordPress can be correctly inserted as variables in PHP headers for Content Security Policy by retrieving the nonce value using the WordPress function `wp_create_nonce()` and then inserting it into the PHP headers using the `header()` function. This ensures that the nonce value is dynamically generated and included in the Content Security Policy headers.

$nonce = wp_create_nonce( 'my_custom_nonce' );
header( "Content-Security-Policy: script-src 'self' 'nonce-$nonce';" );