protected function getPreposition($form, $result = null)
{
$preposition = $this->defaultPrepositions[$form];
if ($result && $form == 'in' && in_array(mb_strtolower(mb_substr($result, 0, 1)), ['в', 'ф']) && !$this->isVowel(mb_substr($result, 1, 1))) {
$preposition .= 'о';
}
return $preposition;
}