Using WordPress ‘apply_filters_deprecated()’ PHP function
The `apply_filters_deprecated()` function in WordPress triggers a deprecation notice and fires the original filter hook when a filter hook is deprecated
PHP
Using WordPress ‘allow_subdirectory_install()’ PHP function
The `allow_subdirectory_install()` function in WordPress allows users to determine if a subdirectory installation is permitted in a Multisite network setup
Using WordPress ‘add_option()’ PHP function
The `add_option()` function in WordPress is used to add a new option to the database, which can be accessed later through the `get_option()` function
Using WordPress ‘add_meta()’ PHP function
Adds post meta data defined in the §_POST superglobal for a post with given ID.