mixed $value, int $user_id, string $context )
Filters the value of a user field in a standard context.
The dynamic portion of the hook name,
$field, refers to the prefixed user field being filtered, such as ‘user_login’, ‘user_email’, ‘first_name’, etc.
(mixed) The user object value to sanitize.
(int) User ID.
(string) The context to filter within.