gistfile1.php

<?php

public function normalizeValue($value, ElementInterface $element = null)
{
    $opts = $this->setOptions();

    $value = array
    (
        'value' => $value,
        'label' => $opts[$value]
    );

    return $value;
}
  
public function serializeValue($value, ElementInterface $element = null)
{
    return parent::serializeValue($value['value'], $element);
}

private function setOptions()
{
    include '_Regions.php';

    $opts;

    if( $this->regionType == 'countries' )
    {
        $opts = $countries;
    }
    elseif( $this->regionType == 'usStates' )
    {
        $opts = array_merge($states, $provinces);
    }

    return $opts;
}