<?php 

//select sanitization function
function kickstarter_sanitize_select( $input, $setting ) {
    // Ensure input is a slug.
    $input = sanitize_key( $input );
    // Get list of choices from the control associated with the setting.
    $choices = $setting->manager->get_control( $setting->id )->choices;
    // If the input is a valid key, return it; otherwise, return the default.
    return ( array_key_exists( $input, $choices ) ? $input : $setting->default );
}

//checkbox sanitization function
function kickstarter_sanitize_checkbox($checked) {
    // Boolean check.
    return ((isset($checked) && true == $checked) ? true : false);
}

//radio box sanitization function
function kickstarter_sanitize_radio( $input, $setting ){
    //removes all HTML markup
    $input = sanitize_text_field($input);
    return $input;
}