A Object
(
    [a1] => 100
    [a2:protected] => 6
    [a3:A:private] => 9
)
f1
Tong =115
A Object
(
    [a1] => 10
    [a2:protected] => 10
    [a3:A:private] => 20
)
Hang so A1=1000
Ham f3...