Replacing valid_email() with filter_var()

According to this description the valid_email() function is deprecated and scheduled for removal in CodeIgniter 3.1+. The web page says that the PHP function filter_var() should be used instead.

But filter_var() takes two arguments, whereas valid_email() only takes one. So how do I specify a two-argument function with a fixed second argument in a form validation list?

For example this example uses this code:

Code:

$this->form_validation->set_rules('email', 'Email', 'required|valid_email|is_unique[users.email]');

How can I replace valid_email here with filter_var with FILTER_VALIDATE_EMAIL as the second argument? Or am I supposed to write my own valid_email() function?

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Claus