src/Date.php
public static function cast($date)
    {
        return $date instanceof self ?
                $date :
                new self($date->format(self::ISO8601), $date->getTimezone());
    }
public static function cast($date)
    {
        return $date instanceof self ?
                $date :
                new self($date->format(self::ISO8601), $date->getTimezone());
    }
Faz o "cast" de \DateTime para p13\datetime\Date
@param \DateTime $date
@return Date