Automattic\WooCommerce\Vendor\League\ISO3166

Guards::guardAgainstInvalidNumeric │ public static │ WC 1.0

Assert that input looks like a numeric key.

Method of the class: Guards{}

No Hooks.

Returns

null. Nothing (null).

Usage

$result = Guards::guardAgainstInvalidNumeric( $numeric ): void;
$numeric(string) (required)
.

Guards::guardAgainstInvalidNumeric() code WC 10.3.6

woocommerce/lib/packages/League/ISO3166/Guards.php 
public static function guardAgainstInvalidNumeric(string $numeric): void
{
    if (1 !== preg_match('/^\d{3}$/', $numeric)) {
        throw new DomainException(sprintf('Not a valid numeric key: %s', $numeric));
    }
}