Custom fields

I’m trying to add the code bellow on my theme functions.php,
but it wont work

Could you help please?

add_filter(‘sln.checkout.additional_fields’,function(){
return array(
‘custom_field_c’=> array(
“label” => ‘Kids’,
“type” => ‘select’,
“options” => array(‘0′,’1’, ‘2’, ‘3’, ‘4’, ‘5’),
“width” => ‘half’,
“default” => ‘0’

),
);
});

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