     
        @param zip: String to verify the containing numbers are either 5 or 9 numbers in length.
        @return Returns &lt;code>true&lt;/code> if zip code; otherwise &lt;code>false&lt;/code>.
    */
    public static function isZip(zip:String):Boolean {
        var l:Number = StringUtil.getNumbersFromString(zip).length;
        return (l == 5 || l == 9);
    }
    
    /**
        Determines if string is a valid state abbreviation.
        
        @param state: String to verify as two letter state 