Extracts a set of option values from a nested options array.
string $key: The key to extract from each array item.
array $options: The options array to return values from.
array A regular one dimensional array of values.
protected static function extractFromOptionsArray($key, $options) {
return array_map(function ($item) use ($key) {
return isset($item[$key]) ? $item[$key] : NULL;
}, $options);
}