static public function equals(QtiDatatype $a = null, QtiDatatype $b = null)
    {
        return (is_null($a) ? is_null($b) : $a->equals($b));
    }
static public function equals(QtiDatatype $a = null, QtiDatatype $b = null)
    {
        return (is_null($a) ? is_null($b) : $a->equals($b));
    }
static public function equals ( QtiDatatype $ a = null , QtiDatatype $ b = null ) { return ( is_null ( $ a ) ? is_null ( $ b ) : $ a -> equals ( $ b ) ) ; }
Whether or not two QtiDatatype instances are equals.

Because the runtime model
also deals with null values, this utility method helps to determine equality
easily, without testing specifically if one or both values are null prior
to perform QtiDatatype::equals().

@param QtiDatatype $a
@param QtiDatatype $b
@return boolean
Whether or not two QtiDatatype instances are equals .