use Symfony\Component\OptionsResolver\Options;

// throws MissingOptionsException if the option(s) is (are) missing
Options::require($options, 'toTz');

// throws InvalidOptionsException if any of the options have an invalid type
Options::validateTypes($options, array(
    'fromTz' => 'string',
    'toTz' => 'string',
    'dateFormat' => 'string',
    'timeFormat' => 'string',
    'calendar' => array('null', 'integer'),
));

// throws InvalidOptionsException if any of the options contain an invalid value
Options::validateValues($options, array(
    'calendar' => array(
        \IntlDateFormatter::GREGORIAN,
        \IntlDateFormatter::TRADITIONAL,
    ),
));

// throws InvalidOptionsException if any of the given options is not known
$options = Options::resolve($options, array(
    'fromTz' => null,
    'toTz' => null,
    'dateFormat' => \IntlDateFormatter::MEDIUM,
    'timeFormat' => \IntlDateFormatter::SHORT,
    'calendar' => \IntlDateFormatter::GREGORIAN,
));